2006 Second Edition TIGER/Line(R) Files Technical Documentation Glossary Active government A governmental unit that is in operation, having elected or appointed officials. An active government may not be raising revenues or providing any services but must have some official with the power to do so. The U.S. Census Bureau differentiates active entities by their fiscal independence and whether they provide general or limited, special services. See also functional status, functioning government, governmental unit, inactive government, nonfunctioning entity. Address The house number and street name, or other designation, assigned to a housing unit, group housing facility, business establishment, or other structure for mail delivery and/or to enable emergency services, delivery people, and visitors to find the structure. See also house number-street name address. Addressable feature A feature along which living quarters can be constructed and assigned an address. Usually, this is a road or street, but it could also be an alley, driveway, and occasionally an unusual feature such as a railroad track or navigable stream. Address Range The lowest and highest actual or potential address numbers used to identify structures along each side of a street feature that has city- type addresses. The U.S. Census Bureau usually expands the range to include all possible numbers; e.g., if the existing addresses on the odd-numbered side of a street are 101, 103, 105, 107, 109, 111, 113, 115, and 117, the U.S. Census Bureau may expand the address range to 101-199. Administrative Unit A nonfunctioning legal entity that provides a framework for the administration of a function performed by another governmental unit or office. Examples of administrative units include certain types of minor civil divisions, such as magisterial districts in West Virginia, in which a member is elected to the County Board of Supervisors; legal voting districts established by the state or county to control elections; certain types of American Indian tribal subdivisions that are established for election purposes; and congressional districts. AIANA See American Indian area, Alaska Native area, Hawaiian home land. AIANA/HHL See American Indian area, Alaska Native area, Hawaiian home land. AIR See American Indian reservation. Alaska Native Regional Corporation (ANRC) A corporate entity organized to conduct both business and nonprofit affairs of Alaska Natives pursuant to the Alaska Native Claims Settlement Act of 1972 (Public Law 92-203, as amended). Twelve ANRCs are legally bounded geographic entities that cover Alaska except for the Annette Islands Reserve (an American Indian reservation). A thirteenth ANRC represents Alaska Natives who do not live in Alaska and do not identify with any of the 12 corporations. The U.S. Census Bureau does not provide data for this ANRC because it has no geographic extent. Alaska Native village (ANV) A local governmental unit in Alaska that constitutes an association, band, clan, community, group, tribe, or village recognized pursuant to the Alaska Native Claims Settlement Act of 1972 (Public Law 92-203, as amended). ANVs do not have clearly defined boundaries that are easily locatable, and they often include many square miles of land used by Alaska Natives for hunting and fishing, so the U.S. Census Bureau works with officials of the Alaska Native villages and Alaska Native Regional Corporations to delineate Alaska Native village statistical areas (ANVSAs) for data presentation purposes. See also Alaska Native village statistical area. Alaska Native village statistical area (ANVSA) A census statistical entity that represents the densely settled portion of an Alaska Native village (ANV) for data presentation purposes. For Census 2000, ANVSAs were reviewed and delineated by officials of the ANVs or the Alaska Native Regional Corporation (ANRC) in which an ANV is located, or by the U.S. Census Bureau. See also Alaska Native village. American Indian area, Alaska Native area, and Hawaiian home land (AIANA/HHL) A U.S. Census Bureau term referring to these entity types: American Indian reservation, American Indian off-reservation trust land, tribal subdivision, Oklahoma tribal statistical area, state designated American Indian statistical area, Alaska Native Regional Corporation, Alaska Native village, Alaska Native village statistical area, and Hawaiian home land. American Indian reservation-Federal (federal AIR) An area that has been set aside by the United States for the use of one or more federally recognized American Indian tribes. The boundary of a federal reservation is defined by tribal treaty, agreement, executive or secretarial order, federal statute, or judicial determination. The U.S. Census Bureau recognizes federal reservations as territory over which American Indian tribes have primary governmental authority. These entities are known as colonies, communities, pueblos, rancherias, ranches, reservations, reserves, tribal towns, and tribal villages. The Bureau of Indian Affairs maintains a list of federally recognized tribal governments. The U.S. Census Bureau contacts representatives of American Indian tribal governments to identify the boundaries for federal reservations. The U.S. Census Bureau contacts the Bureau of Indian Affairs (BIA) or other federal agencies if a tribal government cannot supply the boundaries and/or supporting legal documentation for a boundary change. Federal reservations may cross state, county, county subdivision, and place boundaries. See also American Indian reservation- State, American Indian trust land, joint use area. American Indian reservation-State (state AIR) An area that a state government has allocated to a tribe recognized by that state, but not by the federal government. A governor-appointed state liaison provides the names and boundaries for state recognized American Indian reservations to the U.S. Census Bureau. See also American Indian reservation-Federal, American Indian trust land, joint use area. American Indian tribal subdivision A legal subdivision of federally recognized American Indian reservations, off-reservation trust land, or Oklahoma tribal statistical areas (OTSAs). Tribal subdivisions are known as areas, chapters, communities, or districts. These entities are internal units of self- government or administration that serve social, cultural, and/or economic purposes for American Indians living on reservations, off- reservation trust land, or within the boundaries of an OTSA. The U.S. Census Bureau obtains the boundary and name information for tribal subdivisions from tribal governments. American Indian trust land Areas for which the United States holds title in trust for the benefit of a federally recognized American Indian tribe (tribal trust land) or for an individual American Indian (individual trust land). Trust lands can be alienated or encumbered only by the owner with the approval of the Secretary of the Interior or his/her authorized representative. Trust lands may be located on or off a reservation. The U.S. Census Bureau recognizes and tabulates data for reservations and off- reservation trust lands because American Indian tribes have primary governmental authority over these lands. Primary tribal governmental authority generally is not attached to tribal lands located off the reservation until the lands are placed in trust. In U.S. Census Bureau data tabulations, off-reservation trust lands always are associated with a specific federally recognized reservation and/or tribal government. A tribal government appointed liaison provides the name and boundaries of their trust lands. The U.S. Census Bureau does not identify fee land (or land in fee simple status) or restricted fee lands as specific geographic categories and they are not identified in the TIGER/Line(R) files. See also American Indian reservation and joint use area. ANRC See Alaska Native Regional Corporation. ANV See Alaska Native village. ANVSA See Alaska Native village statistical area. BAS See Boundary and Annexation Survey. BG See block group. BIA See Bureau of Indian Affairs. Block See census block. Block boundary See census block boundary. Block group (BG) A statistical subdivision of a census tract. A block group consists of a cluster of census blocks having the same first digit of their 4-digit identifying number within a census tract. For example, BG 3 includes all blocks within a census tract numbered between 3001 and 3999. A BG may consist of from one to one thousand census blocks. BGs generally contain between 600 and 3000 people, with an optimum size of 1,500 people. The BG is the lowest-level geographic entity for which the U.S. Census Bureau tabulates sample data from a decennial census. BGs were delineated by state, local, and tribal government officials, and by U.S. Census Bureau geographic staff for areas that did not have a participating organization. See also block number. Block number See census block number. Borough A legally established geographic entity in Alaska, which the U.S. Census Bureau treats as equivalent to a county for data presentation purposes; a minor civil division (MCD) in each of the five counties that comprise New York city; a type of incorporated place in Connecticut, New Jersey, and Pennsylvania. The boroughs in New Jersey and Pennsylvania are not part of any MCD, and the U.S. Census Bureau treats them as county subdivisions as well as places for data presentation purposes. See also census area, county subdivision, dependent place, incorporated place, independent place. Boundary and Annexation Survey (BAS) A U.S. Census Bureau survey of counties (and legally equivalent entities), minor civil divisions (MCDs), incorporated places, American Indian reservations, off-reservation trust lands, and tribal subdivisions. The purpose of the BAS is to determine the inventory of legally defined entities and the correct names, political descriptions, and legal boundaries of counties, MCDs, incorporated places, American Indian reservations, off-reservation trust lands, and tribal subdivisions as of January 1 of the year of the survey. The survey also collects specific information on the legal actions that affect boundary changes. Bureau of Indian Affairs (BIA) The Federal Government agency, located in the Department of the Interior, responsible for the historic and legal relation-ships between the Federal Government and American Indian communities. CBSA See Core Based Statistical Area. CCD See census county division. CD See congressional district. CDP See census designated place. CE See circular error. CE95 See circular error 95. CENID Census File Identification Code. The CENID is a U.S. Census Bureau alphanumeric identifier used to uniquely number the GT-polygons within its TIGER(R) partitions. Since the TIGER partitions may include only a portion of a county, a TIGER/Line file may contain multiple CENIDs. Census area A statistical entity that serves as the equivalent of a county in Alaska. Census areas are delineated cooperatively by the state of Alaska and the U.S. Census Bureau for the purpose of presenting census data for the portion of Alaska that is not within an organized borough, city and borough, or municipality. See also borough, city and borough, county, municipality. Census block A geographic area bounded by visible features such as streets, roads, streams, and railroad tracks and by nonvisible boundaries such as city, town, township, and county limits, and short imaginary extensions of streets and roads. Generally, one of these features must be an addressable feature (usually a street or road). Many blocks, such as a block in a city, are small in area, but census blocks in sparsely settled areas may contain many square miles. A block is the smallest geographic entity for which the U.S. Census Bureau collects information and tabulates decennial census data. All territory (both land and water) in the United States, Puerto Rico, and the Island Areas is assigned to a census block. See also tabulation block. Census block boundary A census feature, visible or nonvisible, that delimits a census block. Usually, it takes two or more features to delimit a census block, but a single feature may delimit a census block in the case of an island or a circumferential street. Census block number A four-digit number that identifies a specific block on Census 2000 products. Census 2000 block numbers are not repeated within census tract. See also census block suffix. Census block suffix To accommodate changes in legal entity boundaries occurring after January 1, 2000, the U.S. Census Bureau assigns a current alphabetic suffix for a Census 2000 block number. The current suffixes for Census 2000 block numbers are not permanent and will change with each annual cycle of current block suffixing. See also census block number. Census code A code assigned by the U.S. Census Bureau to identify a specific geographic entity. The U.S. Census Bureau uses census codes for geographic entities for which a Federal Information Processing Standard (FIPS) code either does not exist or is inadequate to identify and/or sequence a type of entity. See also Federal Information Processing Standards, geographic code. Census county division (CCD) A statistical subdivision of a county, established and delineated cooperatively by the U.S. Census Bureau and state, local, and tribal officials for data presentation purposes. The U.S. Census Bureau established CCDs in 21 states that do not have minor civil divisions (MCDs) suitable for data presentation; that is, MCDs have not been legally established, do not have a governmental or administrative purpose, have boundaries that are ambiguous or change frequently, and/or generally are not well known to the public. A CCD boundary normally follows visible features and county lines and in most cases coincides with census tract boundaries. See also county subdivision, minor civil division. Census designated place (CDP) A geographic entity that serves as the statistical counterpart of an incorporated place for the purpose of presenting census data for an area with a concentration of population, housing, and commercial structures that is identifiable by name, but is not within an incorporated place. CDPs usually are delineated cooperatively with state, Puerto Rico, Island Area, local, and tribal officials following U.S. Census Bureau guidelines. For Census 2000, for the first time, CDPs did not have to meet a minimum population threshold to qualify for the tabulation of census data. CDP boundaries usually coincide with visible features or the boundary of an adjacent incorporated place or county line. CDP boundaries may change with changes in the settlement pattern; a CDP with the same name as in a previous census does not necessarily have same boundary. CDPs in Puerto Rico are called comunidades and zonas urbanas. CDPs were referred to as unincorporated places for the1970 and earlier censuses. See also comunidad. economic census place, incorporated place, place, zona urbana. Census feature class code (CFCC) Developed by the U.S. Census Bureau to identify the most prominent characteristics of a feature, the CFCC, as used in the TIGER/Line files, is a three-character code. The first character is a letter describing the feature class; the second and third characters are numbers representing the major and minor categories. Census subarea A statistical subdivision of a borough, city and borough, municipality, and census area (statistical equivalent of a county) in Alaska. A census subarea is similar to a census county division (CCD) in other states. Census subareas are delineated cooperatively by the State of Alaska and the U.S. Census Bureau. See also county subdivision. Census tract A small, relatively permanent statistical subdivision of a county or statistically equivalent entity, delineated for data presentation purposes by a local group of census data users in accordance with U.S. Census Bureau guidelines. The U.S. Census Bureau delineated census tracts in situations where no local participant existed or where local or tribal governments declined to participate. Census tract boundaries normally follow relatively permanent visible features, but may follow governmental unit boundaries and other nonvisible features in some instances; they always nest within counties or statistically equivalent entities. Designed to be relatively homogeneous units with respect to population characteristics, economic status, and living conditions at the time data users established them, census tracts generally contain between 1,500 and 8,000 inhabitants. The spatial size of census tracts varies widely depending on the density of settlement. Census tract boundaries are delineated with the intention of being maintained over a long time so that statistical comparisons can be made from census to census. However, physical changes in street patterns caused by highway construction, new developments, and so forth, may require boundary revisions. Census tracts occasionally are split due to population growth or combined as a result of substantial population decline. They may be split by any subcounty geographic entity. See also census tract number, tribal census tract. Census tract number A four-digit number, which might be followed by a two-digit decimal suffix, used to identify a census tract. Census tract numbers are always unique within a county or statistically equivalent entity. Census tract numbers range from 0001 to 9999. Census tract suffixes may range from .00 to .98. For Census 2000, the U.S. Census Bureau reserved the basic census tract numbers 9400 to 9499 for census tracts delineated within or to encompass American Indian reservations or off-reservation trust land that may exist in multiple states or counties. The U.S. Census Bureau uses census tract number 0000 to identify a census tract delineated to provide complete coverage of water area in territorial seas and the Great Lakes. Leading zeros are not shown on the U.S. Census Bureau's maps. Central city In a metropolitan area (MA), the largest place and, in some areas, one or more additional places that met official standards issued by the federal Office of Management and Budget (OMB). If a place extended beyond an MA, only the portion within the MA was a central city. A few Primary Metropolitan Statistical Areas (PMSAs) did not have a central city. The OMB replaced the term "central city" with the term "principle city" on June 6, 2003. The OMB made this change because the term "central city" had come to connote "inner city" and thus sometimes caused confusion. See also central place and principal city. Central county The county or counties of a Core Based Statistical Area containing a substantial portion of an urbanized area or urban cluster or both, and to and from which commuting is measured to determine qualification of outlying counties. See also Core Based Statistical Area, Metropolitan Statistical Area, Micropolitan Statistical Area. Central place In an urban area (urbanized area or urban cluster), the largest place and, in some areas, one or more additional places that meet specific U.S. Census Bureau criteria. If a place is identified as an extended place, only the portion within the urban area represents the central place. For an urban area that does not contain an incorporated or census designated place, there is no central place, and the title of the urbanized area or urban cluster uses the name of a minor civil division, or a local place name recognized by the Board on Geographic Names and recorded by the U.S. Geological Survey. See also central city. CFCC See census feature class code. Circular error (CE) An accuracy figure representing the stated percentage of probability that any point expressed as a function of two linear components (eg., horizontal position) will be within the given circle. See also circular error 95. Circular error 95 (CE95) The CE95 represents the circular error of the data. The number represents the accuracy of the a road centerline file in meters with 95 percent confidence; meaning that 95 percent of the coordinate positions in the dataset will have an error relative to ground truth that is equal to or smaller than the value reported. For example, if a GPS position measurement is accurate to 5 meters CE95, this means that there is a 95 percent probability that the measurement lies inside a circle with a radius of 5 meters. This also means that there is a 5 percent probability that the measurement lies outside the 5-meter radius circle. See also circular error. City A type of incorporated place in all states and the District of Columbia. In agreement with the state of Hawaii, the U.S. Census Bureau does not recognize the city of Honolulu for presentation of census data. In Virginia, all cities are not part of any county, and so the U.S. Census Bureau treats them as equivalent to a county, as well as treating them as places, for data presentation purposes; there also is one such "independent city" in each of three states: Maryland, Missouri, and Nevada. In 23 states and the District of Columbia, some or all cities are not part of any minor civil division (MCD), and the U.S. Census Bureau also treats them as county subdivisions, statistically equivalent to MCDs, for data presentation purposes. See also consolidated city, county subdivision, dependent place, incorporated place, independent city, independent place, place. City and borough A legally established geographic entity in Alaska. The U.S. Census Bureau treats a "city and borough" as equivalent to a county for data presentation purposes. The U.S. Census Bureau also treats the "city and boroughs" in Alaska as incorporated places. See also borough, census area, county, municipality, county equivalent. City-style address See house number-street name address. CMSA See Consolidated Metropolitan Statistical Area. CNECTA See Combined New England City and Town Area. Code See census code, Federal Information Processing Standards, geographic code. Collection geography The geographic entities used by the U.S. Census Bureau for taking a census. Combined New England City and Town Area A geographic entity consisting of two or more adjacent New England City and Town Areas (NECTAs) with employment interchange measures of at least 15. The NECTAs that combine retain separate identities within the larger combined statistical area. Combined New England City and Town Areas were first defined by the federal Office of Management and Budget on June 6, 2003. See also Core Based Statistical Area, Metropolitan Statistical Area, Micropolitan Statistical Area, New England City and Town Area. Combined Statistical Area A geographic entity consisting of two or more adjacent Core Based Statistical Areas (CBSAs) with employment interchange measures of at least 15. The CBSAs that combine retain separate identities within the larger combined statistical area. Combined Statistical Areas were first defined by the federal Office of Management and Budget on June 6, 2003. See also Core Based Statistical Area, Metropolitan Statistical Area, Micropolitan Statistical Area. Commercial Region For purposes of economic census data presentations, the municipios in Puerto Rico are grouped into nine Commercial Regions. Complete chain A chain (a sequence of non-intersecting line segments) that explicitly references left and right polygons and start and end nodes. The shape points combine with the nodes to form the segments that make a complete chain. Commonwealth The legal designation for four states (Kentucky, Massachusetts, Pennsylvania, and Virginia), Puerto Rico, and the Northern Mariana Islands. The U.S. Census Bureau does not use this term in its data presentations. Comunidad A census designated place (CDP) in Puerto Rico that is not related to a municipio's seat of government. Formerly called an aldea in 1980 and earlier censuses. See also census designated place, zona urbana. Congressional district (CD) One of 435 areas established by law for the election of people to the U.S. House of Representatives. In general, congressional districts (CDs) are established by state legislation or the courts. Within each state, these areas must contain, as nearly as possible, an equal number of inhabitants. The number of CDs in each state may change after each decennial census, and the boundaries may be changed more than once during a decade. Consolidated city A type of incorporated place that contains one or more other incorporated places that continue to function as separate govern-mental units even though they are part of a consolidated government; for example, a village that continues to function as a separate, active govern-mental entity even though it is part of a city-county government. See also consolidated government. Consolidated government A consolidated government exists when the functions of two types of governmental entities are combined into a single government although there may be two different sets of officials administering each function. Examples of consolidated governments are county-incorporated place consolidations, minor civil division-incorporated place consolidations, and county-minor civil division consolidations. The combined governmental units may or may not occupy exactly the same territory. See also consolidated city. Consolidated Metropolitan Statistical Area (CMSA) For Census 2000, a geographic entity designated by the federal Office of Management and Budget (OMB) for use by federal statistical agencies. An area became a CMSA if it qualified as a metropolitan area (MA), had a census population of one million or more, had component parts that were recognized as Primary Metropolitan Statistical Areas (PMSAs) based on official standards, and local opinion favored the designation. CMSAs consisted of whole counties except in New England, where they consisted of county subdivisions (primarily cities and towns). New standards for Core Based Statistical Areas replaced and superseded CMSAs on June 6, 2003. See also central city, metropolitan area, Metropolitan Statistical Area, New England County Metropolitan Area, Primary Metropolitan Statistical Area, and Core Based Statistical Area. Core A densely settled concentration of population, comprising either an urbanized area (of 50,000 or more population) or an urban cluster (of 10,000 to 49,999 population) around which a Core Based Statistical Area (CBSA) is defined. See also Core Based Statistical Area, Metropolitan Statistical Area, Micropolitan Statistical Area. Core Based Statistical Area (CBSA) A statistical geographic entity consisting of the county or counties associated with at least one core (urbanized area or urban cluster) of at least 10,000 population, plus adjacent counties having a high degree of social and economic integration with the core as measured through commuting ties with the counties containing the core. Metropolitan and Micropolitan Statistical Areas are the two categories of Core Based Statistical Areas. Core Based Statistical Areas were first defined by the federal Office of Management and Budget on June 6, 2003. See also Metropolitan Statistical Area, Micropolitan Statistical Area, Metropolitan Division New England City and Town Area, New England City and Town Area Division, Principle City, Outside Core Based Statistical Area, central county, main city or town, main county, outlying county, secondary county. Core Based Statistical Area code The Metropolitan Statistical Areas, Micropolitan Statistical Areas, New England City and Town Areas (NECTAs), Metropolitan Divisions, and New England City and Town Area (NECTA) Divisions are identified using a 5- digit numeric code. The codes for metropolitan and micropolitan statistical areas and metropolitan divisions are assigned in alphabetical order by area title and fall within the 10000 to 59999 range. Metropolitan divisions are distinguished by a 5-digit code ending in "4." NECTA and NECTA Division codes fall within the 70000 to 79999 range and are assigned in alphabetical order by area title. NECTA Divisions are distinguished by a 5-digit code ending in "4." The Combined Statistical Area and Combined New England City and Town Areas are identified using a 3-digit numeric code. Combined Statistical Area codes fall within the 100 to 599 range. Combined NECTA codes fall within the 700 to 799 range. See also Federal Information Processing Standards, Metropolitan Area codes. Corporate corridor A narrow strip of land, generally consisting of all or part of the right-of-way of a road, proposed road, power line, or similar feature, that is part of an incorporated place; a corridor also may exist without relation to any accompanying visible feature. Count Question Resolution (CQR) The CQR Program was an administrative review program that handled external challenges to official Census 2000 counts of housing units and group quarters population received from state, local or tribal officials of governmental entities in the U.S. and Puerto Rico. The CQR Program was in existence from June 30, 2001 to September 30, 2003. It corrected errors in boundaries, geocoding (assignment of addresses, structures, or key geographic locations identified by one or more geographic codes), and/or coverage (specific living quarters and persons residing therein that were identified during the Census 2000 process but erroneously included or excluded due to processing mistakes). The CQR program was not a mechanism or process to challenge the March 6, 2001, decision of the Secretary of Commerce to release unadjusted Census 2000 redistricting data. No changes were made to the apportionment or redistricting counts as a result of the CQR program. County A type of governmental unit that is the primary legal subdivision of every state except Alaska and Louisiana. A number of geographic entities are not legally designated as a county, but are recognized by the U.S. Census Bureau as equivalent to a county for data presentation purposes. These include the boroughs, city and borough, municipality, and census areas in Alaska; parishes in Louisiana; and cities that are independent of any county (independent cities) in Maryland, Missouri, Nevada, and Virginia. They also include the municipios in Puerto Rico, districts and islands in American Samoa, municipalities in the Northern Mariana Islands, and islands in the Virgin Islands of the United States. Because they contain no primary legal divisions, the U.S. Census Bureau treats the District of Columbia and Guam each as equivalent to a county (as well as equivalent to a state) for data presentation purposes. In American Samoa, a county is a minor civil division (MCD). See also borough, census area, city and borough, county equivalent, municipality, parish, economic census county. County code A three-digit Federal Information Processing Standards (FIPS) code that identifies each county and statistically equivalent entity within a state. The U.S. Census Bureau assigns the codes within a state based on the alphabetic sequence of county names within that state leaving gaps in the numbering system to accommodate new counties or statistically equivalent entities. See also Federal Information Processing Standard. County equivalent A geographic entity that is not legally referred to as a county, but is recognized by the U.S. Census Bureau as equivalent to a county for purposes of data presentation. See also borough, census area, city and borough, independent city, municipality, municipio, parish. County subdivision The primary legal or statistical division of a county or statistically equivalent entity recognized by the U.S. Census Bureau for data presentation. County subdivisions include census county divisions (in 21 states), census subareas (in Alaska), minor civil divisions (in 28 states), and unorganized territories (in 10 states); incorporated places independent of any minor civil division in all or part of 23 states and the District of Columbia; barrios and barrios-pueblo in Puerto Rico; and a variety of legal entities in the Island Areas. See also census county division, city, minor civil division, town, township, unorganized territory. CNECTA See Combined New England City and Town Area. CQR See Count Question Resolution Program. Crews-of-vessels The shipboard populations of U.S. Navy, U.S. Coast Guard, and merchant ships, but not the inhabitants of houseboats or marinas. For geographic purposes, the population of each ship is assigned to a census tract and census block that includes the ship's home port (Navy and Coast Guard) or that contains the facility, pier, or dock associated with the ship. The land block will contain a point landmark with a census feature class code (CFCC) of D25. CSA See Combined Statistical Area. Dependent place An incorporated place or CDP that is legally or statistically part of the county(ies) and/or county subdivision(s) within which it is located; the statistical data for the place also are tabulated as part of the total for the county(ies) and/or county subdivision(s) that these data are part of. There are three types of dependent places: (1) an incorporated place that is legally part of the county(ies) and/or MCD(s) within which it is located, (2) an incorporated place that is legally part of the county(ies) and statistically part of the county subdivision(s) within which it is located, and (3) a CDP that always is statistically part of the county(ies) and county subdivision(s) within which it is located. See also incorporated place, independent place. Digital Line Graph (DLG) A computer-readable file, produced by the USGS, of geographic information that covers the same extent as a quadrangle map. DLG See Digital Line Graph. Economic Census County The geographic entities recognized as counties or statistically equivalent entities for the Economic Censuses differs some-what from that used in decennial censuses. Refer to the Economic Census Geography section of Chapter 4 for more information. See also county. Economic Census Place Qualification of economic census places is based on a population threshold of 2,500. There are other differences between the geographic entities recognized as places for the Economic Census and those recognized in decennial censuses. Refer to the Economic Census Geography section of Chapter 4 for more information. See also census designated place, incorporated place, place. Elementary school district A school district inclusive of kindergarten through either the eighth or ninth grade or the first through either the eighth or the ninth grade. See also school district, secondary school district, unified district. Entity point A point used for identifying the location of point features (or areal features collapsed to a point), such as towers, places, and so forth. Extended city See Extended Place. Extended Place A place that contains both urban and rural territory; i.e., an incorporated place or census designated place (CDP) that is partially within and partially outside of an urbanized area or urban cluster. The term is first used for Census 2000. Previously referred to as an "extended city," which applied only to incorporated places, subject to very specific criteria. See also rural, rural place, urban, urban place. FEAT The TIGER/Line file field name for the alternate feature identification code used as a pointer between record types. The FEAT links geographic objects to an alternate or secondary name. Feature See linear feature. Federal Information Processing Standard (FIPS) A set of numeric and/or alphabetic codes issued by the National Institute of Standards and Technology (NIST) to ensure uniform identification of geographic entities (and other computer data) throughout all federal government agencies. Fictitious entity An entity created at one level of the U.S. Census Bureau's geographic hierarchy that is coextensive or completes a remainder with a legal entity that functions in a different level of the hierarchy. Examples include fictitious county and minor civil divisions created for independent cities, that is, incorporated places that are primary divisions of a state existing outside of counties (such as the 39 Virginia independent cities), minor civil divisions created in the Northeast states that are coextensive with incorporated places that are themselves primary divisions of the county, and the place (balance) entities of consolidated cities. FIPS See Federal Information Processing Standard. FIPS class code Comprised of four major "groups," the FIPS class code differentiates between populated places, other geopolitical and census units, institutional facilities, and terminated entities. The U.S. Census Bureau uses only a subset of the classes within each group for its needs. See also Federal Information Processing Standard. FIPS code FIPS codes are assigned for a variety of geographic entities including American Indian area, Alaska Native area, Hawaiian home land, congressional district, county, county subdivision, metropolitan area, place, and state. See also Federal Information Processing Standard. Functional status The classification of a geographic entity as a legal or statistical entity. It further identifies a legal entity as an active, inactive, false, functioning, or nonfunctioning government and, if active, denotes it fiscal independence and whether it provides general or limited, special services. Functional status determines an entity's eligibility to participate in various U.S. Census Bureau programs. Functioning government A legal entity that has the ability to have either elected or appointed officials that have the power to raise revenue though taxes to provide general-purpose public or specialized services. The powers of governmental units are established by law. See also active government, governmental unit, inactive government, nonfunctioning entity. GBF/DIME-File (Geographic Base File/Dual Independent Map Encoding File) A geographic base file created by the U.S. Census Bureau for the 1970 and 1980 censuses, usually in cooperation with local officials, representing the line segments and related geographic attributes that comprised all or part of the urban cores of metropolitan areas. Each file contained the name of each segment of a mapped feature, its associated address range and ZIP Code(R) if applicable, 1980 census geographic area information for both sides of each segment, node numbers that identified feature intersections and selected points of a curved line, and x, y coordinate information for each node in the file. The file contained information describing the street network in the major urban centers, and was used to build the TIGER database. Geocode To assign, manually or by computer, an address or a living quarters, business, farm, or other structure or establishment to one or more geographic codes, as appropriate, that identify the geographic entity(ies) in which it is located. Geographic code A code, consisting of one or more alphanumeric or special-text characters, used to identify a specific geographic entity. See also census code, Federal Information Processing Standard. Geographic entity A spatial unit of any type, legal or statistical, such as the United States, an American Indian reservation, state, county, county subdivision, place, census tract, block group, or census block. Every geographic entity recognized by the U.S. Census Bureau for data collection or tabulation has a name or other identifier, and most named entities are also represented by a geographic code; the code may serve as the identifier, such as the number assigned to a census tract or census block. See also Federal Information Processing Standard, legal entity, statistical entity. Geographic Information System (GIS) A computer system for the storage, retrieval, and maintenance of information about the points, lines, and areas that represent the streets and roads, rivers, railroads, geographic entities, and other features on the surface of the Earth-information that previously was available only on paper maps. Geometry The part of mathematics dealing with coordinate location and shape. See also geometry and topology, topology. Geometry and Topology These combined characteristics are the logical, mathematical framework upon which geographic objects are manipulated in a GIS. See also geometry, topology. GIS See Geographic Information System. Global Positioning System (GPS) A world-wide satellite navigation system formed by a constellation of 24 satellites and their ground stations developed by the U.S. Department of Defense. The satellites transmit signals that allow a GPS receiver anywhere on earth to calculate its own location. Governmental unit (GU) A legal entity that has the ability to have either elected or appointed officials that have the power to raise revenue through taxes to provide general-purpose public or specialized services. The powers of GUs are established by law. Some GUs do not have officials or do not implement the powers that the law entitles them to; the U.S. Census Bureau refers to these entities as inactive governmental units. See also active government, fictitious entity, functioning government, inactive government, legal entity. GPS See Global Positioning System. GT See Geometry and Topology. GT-Polygon An area that is an atomic two-dimensional component of one and only one two-dimensional manifold. GT-polygons are elementary polygons that are mutually exclusive and completely exhaust the surface. See also geometry, geometry and topology, topology. Hawaiian home land (HHL) An area held in trust for the benefit of native Hawaiians by the state of Hawaii, pursuant to the Hawaiian Homes Commission Act of 1920, as amended. HHL See Hawaiian home land. House number-street name address An address consisting of a structure number and street name; for example, 201 Main St. The house number may include a fraction (e.g., 11 1/2) or an alphabetic suffix (e.g., 11A). The address may or may not be used for the delivery of mail, and may include apartment numbers/designations or similar identifiers. Inactive government A governmental unit that is not in operation, having no elected or appointed officials and not providing services. See also active government, functioning government, governmental unit. Incorporated place A type of governmental unit, incorporated under state law as a city, city and borough, municipality (except in the Commonwealth of the Northern Mariana Islands), town (except in New England, New York, and Wisconsin), borough (except in Alaska and New York), or village, generally to provide a wide array of specific governmental services for a concentration of people within legally prescribed boundaries. See also dependent place, economic census place, independent place. Independent city An incorporated city that is independent-i.e., not part-of any county. All incorporated places classified as cities in Virginia are independent cities, as are Baltimore, MD; St. Louis, MO; and Carson City, NV. The U.S. Census Bureau treats an independent city as an incorporated place and as equivalent to a county and, where appropriate, a county subdivision for data presentation purposes. See also census designated place, incorporated place, place. Independent place In a state in which the U.S. Census Bureau recognizes minor civil divisions (MCDs), an incorporated place that is not legally part of any MCD. The U.S. Census Bureau treats independent places as equivalent to a county subdivision (an MCD) and as an incorporated place for data tabulation purposes. Independent places exist in 23 states and the District of Columbia. See also dependent place, incorporated place, place. Indian reservation See American Indian reservation. Internal point A coordinate value for a point that lies within its geographic area; where possible, the internal point also is a centroid. Island Areas of the United States The Island Areas of the United States are American Samoa, Guam, the Commonwealth of the Northern Mariana Islands (Northern Mariana Islands), and the Virgin Islands of the United States. The U.S. Census Bureau treats the Island Areas as the statistical equivalents of states for data presentation purposes. Joint use area Territory that is administered, claimed, and/or used by two or more American Indian tribes. It may consist of overlap of territory of adjoining American Indian reservations or Oklahoma tribal statistical areas, or off-reservation trust land for one tribe that is located within the reservation of another tribe. The U.S. Census Bureau designates both legal and statistical joint use areas as unique geographic entities for the purpose of presenting statistical data. KGL See key geographic location. Key geographic location (KGL) A KGL represents a special class of ad-dress information. It provides a geocoding tool like address ranges, but also identifies a spatial object similar to a landmark. The U.S. Census Bureau uses KGLs to identify named building where the use of the feature name enhances the ability to geocode. Because the U.S. Census Bureau is required to suppress all single address-address ranges or basic street addresses to protect the confidentiality of individual addresses collected through census field operations as specified by Title 13 of the U.S. Code, KGLs do not appear in the TIGER/Line files. LAND Landmark Feature Identification Number. A temporary number that uniquely identifies both point and area landmarks within each county file. The LAND is a dynamic number that changes between different versions of the TIGER/Line files. Legal entity A geographic entity with boundaries established by law or real property deed. The U.S. Census Bureau collects legal boundaries through various surveys and operations. Legal entities include states, counties, minor civil divisions, incorporated places, American Indian reservations, off- reservation trust land, and Alaska Native Regional Corporations. See also fictitious entity, governmental unit, statistical entity. Legal/statistical area description (LSAD) The type of a geographic entity in terms of its legal status (e.g., county, city) or the U.S. Census Bureau's statistical area terminology (e.g., census county division, unorganized territory, census designated place). The LSAD for an entity is appended to the entity's name as a prefix or suffix; the LSAD can be blank if an entity does not have a legal description. See also fictitious entity, governmental unit, legal entity, statistical entity. Legislative district An area from which a person is elected to serve in a state legislative body. See also state legislative district, voting district. Linear feature A feature, such as a railroad, road, street, stream, pipeline, or boundary that can be represented by a line in a geographic database. Local ID A unique locally assigned local identification number, that was not automatically assigned by GIS software, attached to a complete chain in a locally provided source file. LSAD See legal/statistical area description. MA See metropolitan area. MAF See master address file. MAF/TIGER Accuracy Improvement Project In 2002 the U.S. Census Bureau began a multi-year project, the MAF/TIGER Accuracy Improve-ment Project (MTAIP), to realign street features in the TIGER database. The U.S. Census Bureau is realigning the street features in a portion of the nation's counties each year until all counties are completed in 2008. See also Master Address File, TIGER(R) database. Main city or town A city or town that acts as an employment center within a New England City and Town Area (NECTA) that has a core with a population of at least 2.5 million. A main city or town serves as the basis for defining a New England City and Town Area Division. See also Core Based Statistical Area, New England City and Town Area, New England City and Town Area Division. Main county A county that acts as an employment center within a Core Based Statistical Area (CBSA) that has a core with a population of at least 2.5 million. A main county serves as the basis for defining a Metropolitan Division. See also Core Based Statistical Area, Metropolitan Statistical Area, Metropolitan Division. Master Address File (MAF) The U.S. Census Bureau's computer-readable file of all addresses and physical/location descriptions, both residential and nonresidential, known to the U.S. Census Bureau for the United States, Puerto Rico, and the Island Areas. Each address is linked to a side of a street segment in the TIGER database if it is possible to do so. MCD See minor civil division. Metropolitan area (MA) A collective term, established by the Office of Management and Budget (OMB) and used for the first time in 1990, to refer to Metropolitan Statistical Areas (MSAs), Consolidated Metropolitan Statistical Areas (CMSAs), and Primary Metropolitan Statistical Areas (PMSAs). In addition, there was an alternative set of areas termed New England County Metropolitan Areas (NECMAs). A set of new standards for Core Based Statistical Areas replaced and superseded MSAs, CMSAs, PMSAs, and NECMAs on June 6, 2003. See also Metropolitan Statistical Area, Consolidated Metropolitan Statistical Area, Primary Metropolitan Statistical Area, New England County Metropolitan Area, Core Based Statistical Area. Metropolitan Area code The National Institute of Standards and Technology (NIST) issued numeric FIPS codes for MAs. FIPS codes for MSAs and PMSAs (and NECMAs) were four-digit codes; CMSAs were assigned two-digit FIPS codes. NIST also made available an alternative set of four-digit codes for CMSAs. New standards for Core Based Statistical Areas (CBSAs) replaced and superseded metropolitan areas on June 6, 2003. See also Federal Information Processing Standards, Core Based Statistical Area codes. Metropolitan Division A county or group of counties within a Core Based Statistical Area that contains a core with a population of at least 2,5 million. A Metropolitan Division consists of one or more main/secondary counties that represent an employment center or centers, plus adjacent counties associated with the main county or counties through commuting ties. Core Based Statistical Areas were first defined by the federal Office of Management and Budget on June 6, 2003. See also Core Based Statistical Area, Metropolitan Statistical Area, New England City and Town Area, New England City and Town Area (NECTA) Division. Metropolitan statistical area A Core Based Statistical Area associated with at least one urbanized area that has a population of at least 50,000. The Metropolitan Statistical Area comprises the central county or counties containing the core, plus adjacent outlying counties having a high degree of social and economic integration with the central county as measured through commuting. Core Based Statistical Areas were first defined by the federal Office of Management and Budget on June 6, 2003. For Census 2000, a Metropolitan Statistical Area (MSA) was a core area with a large population nucleus, together with adjacent communities that had a high degree of economic and social integration with that core. Qualification of an MSA for Census 2000 required the presence of a city with 50,000 or more inhabitants, or the presence of an urbanized area (UA) and a total population of at least 100,000 (75,000 in New England). The county or counties containing the largest city and surrounding densely settled territory were central counties of the Census 2000 MSA. Additional outlying counties qualified to be included in the MSA for Census 2000 by meeting certain other criteria of metropolitan character, such as a specified minimum population density or percentage of the population that was urban. For Census 2000, MSAs in New England were defined in terms of cities and towns, following rules concerning commuting and population density. MSAs were first defined and effective June 30, 1983. See also Core Based Statistical Area, Micropolitan Statistical Area, Metropolitan Division, Consolidated Metropolitan Statistical Area, metropolitan area, Metropolitan Statistical Area, Primary Metropolitan Statistical Area. Micropolitan Statistical Area A Core Based Statistical Area associated with at least one urban cluster that has a population of at least 10,000, but less than 50,000. The Micropolitan Statistical Area comprises the central county or counties containing the core, plus adjacent outlying counties having a high degree of social and economic integration with the central county as measured through commuting. Core Based Statistical Areas were first defined by the federal Office of Management and Budget on June 6, 2003. See also Core Based Statistical Area, Metropolitan Statistical Area. Minor civil division (MCD) A type of governmental unit that is the primary legal subdivision of a county or statistically equivalent entity in many states and statistically equivalent entities, created to govern or administer an area rather than a specific population. MCDs are identified by a variety of terms, such as town, township, or district. The U.S. Census Bureau recognizes MCDs in 28 states, the District of Columbia, Puerto Rico, and the Island Areas. In 20 states and American Samoa, all or many MCDs are active general-purpose governmental units. Many MCDs are not general- purpose governmental units, and therefore do not have elected officials to carry out legal functions; instead, they serve as nonfunctioning administrative entities. See also census county division, county subdivision, fictitious entity, governmental unit, incorporated place, independent place, legal entity, unorganized territory. Minor civil division (MCD) code A five-digit numeric code assigned by the U.S. Geological Survey (USGS) to identify populated places, primary county divisions, and other locational entities within a state. The USGS assigns the codes based on the alphabetic sequence of the entity names; it documents these codes in FIPS 55. See also Federal Information Processing Standard. MSA See Metropolitan Statistical Area. MTAIP See MAF/TIGER Accuracy Improvement Project. Municipality A general term often used to describe incorporated places in all states and minor civil divisions (MCDs) in the New England states. A legally established entity in Alaska and the Commonwealth of the Northern Mariana Islands. The U.S. Census Bureau treats a municipality as equivalent to a county for data presentation purposes. The U.S. Census Bureau also treats the municipality (Anchorage) in Alaska as an incorporated place. See also borough, census area, city and borough, county, county equivalent. Municipio A type of governmental unit that is the primary legal subdivision of Puerto Rico; the U.S. Census Bureau treats the municipio as the statistical equivalent of a county for data presentation purposes. National Hydrography Dataset (NHD) A comprehensive set of digital spatial data that contains information about surface water features such as lakes, ponds, streams, rivers, springs and wells. It identifies the stream segments or reaches that make up the nation's surface water drainage system. The NHD is based upon the content of the U.S. Geological Survey (USGS) Digital Line Graph (DLG) hydrography data integrated with reach-related information from the Environmental Protection Agency (EPA) Reach File Version 3 (RF3). See also reach, reach code. Native Hawaiian Area (NHA) See Hawaiian Home Land. NECMA See New England county metropolitan area. NECTA See New England City and Town Area. Network chains A chain that explicitly references start and end nodes and not left and right polygons. New England City and Town Area (NECTA) A statistical geographic entity that is defined using cities and towns as building blocks and that is conceptually similar to the Core Based Statistical Areas in New England (which are defined using counties as building blocks). NECTAs were first defined by the federal Office of Management and Budget on June 6, 2003. See also Core Based Statistical Area, Metropolitan Statistical Area, Micropolitan Statistical Area, New England City and Town Area Division. New England City and Town Area (NECTA) Division A city or town or group of cities and towns within a New England City and Town Area (NECTA) that contains a core with a population of at least 2.5 million. A NECTA Division consists of a main city or town that represents an employment center, plus adjacent cities and towns associated with the main city or town, or with other cities and towns that are in turn associated with the main city or town, through commuting ties. NECTA Divisions were first defined by the federal Office of Management and Budget on June 6, 2003. See also Core Based Statistical Area, New England City and Town Area, Metropolitan Division. New England county metropolitan area (NECMA) A county based area designated by the federal Office of Management and Budget, and used in Census 2000, as an alternative to the city- and town-based New England Metropolitan Statistical Areas (MSAs) and Consolidated Metropolitan Statistical Areas (CMSAs). New standards for Core Based Statistical Areas replaced and superseded NECMAs effective June 6, 2003. See also Consolidated Metropolitan Statistical Area, metropolitan area, Metropolitan Statistical Area, Primary Metropolitan Statistical Area, and Core Based Statistical Area. NHA See Native Hawaiian Area. NHD See National Hydrography Dataset. Node A zero-dimensional object that is a topological junction of two or more links or chains, or an end point of a link or chain. Noncity-style address A mailing address that does not use a house number and street name, including rural routes (RR) and highway contract routes (HCR), which may include a box number; post office boxes and drawers; and general delivery. See also house number-street name address. Nonfunctioning entity A legal entity that does not have the ability to either elect or appoint officials or the power to raise revenue through taxes to provide general-purpose public or specialized services. The purpose of nonfunctioning units is established by law. Some types of nonfunctioning entities, such as congressional districts, have an official elected to serve the constituents. However, the election of an official to serve on a governing body administering to a larger entity (in this case, the Nation) is different from the officials of a governmental unit elected to directly administer that geographic entity (such as the mayor of a city). See also legal entity. Off-reservation trust land See American Indian trust land. Oklahoma tribal statistical area (OTSA) A statistical entity identified and delineated by the U.S. Census Bureau in consultation with federally recognized American Indian tribes in Oklahoma that once had a reservation in that state. The boundary of an OTSA is that of the former reservation in Oklahoma, except where modified by agreements with neighboring tribes for statistical data presentation purposes. OTSA See Oklahoma tribal statistical area. Outlying county A county that qualifies for inclusion in a Core Based Statistical Area (CBSA) on the basis of commuting ties with the Core Based Statistical Area's central county or counties. See also Core Based Statistical Area, Metropolitan Statistical Area, Micropolitan Statistical Area, central county, main county. Outside Core Based Statistical Areas Counties that do not qualify for inclusion in a Core Based Statistical Area (CBSA) See also Core Based Statistical Area, Metropolitan Statistical Area, Micropolitan Statistical Area. Parish A governmental unit that is the primary legal subdivision of Louisiana. The U.S. Census Bureau treats a parish as equivalent to a county in other states for data presentation purposes. See also county, county equivalent. Peano key A method of combining coordinates into a single key code composed of alternating longitude and latitude digits and used primarily for nearest point searches. Named for Giuseppe Peano, a 19th century Italian mathematician who proved that two-dimensional space could be considered as a one-dimensional line. PL See Public Law. Place A concentration of population either legally bounded as an incorporated place, or delineated for statistical purposes as a census designated place (CDP). Incorporated places have legal/statistical descriptions of borough (except in Alaska and New York), city, city and borough, municipality (except in the Commonwealth of the Northern Mariana Islands), town (except in New England, New York, and Wisconsin), or village. See also census designated place, economic census place, incorporated place. Place code A five-digit numeric code assigned by the U.S. Geological Society (USGS) to identify populated places, primary county divisions, and other locational entities within a state. The USGS assigns the codes based on the alphabetic sequence of the entity names; it documents the codes in FIPS PUB 55. See also Federal Information Processing Standard. Place description code A code assigned by the U.S. Census Bureau to identify whether or not a place is a central place of an urban area or a central city of a metropolitan area (MA). Also used by the U.S. Census Bureau to distinguish those voting districts a state has identified as being an actual voting district, those a state has identified as being a pseudo- voting district, or where a state did not indicate to the U.S. Census Bureau whether or not the voting district followed the actual boundaries of a voting district or is a pseudo-voting district. PMSA See Primary Metropolitan Statistical Area. Point See entity point. POLYID Polygon Identification Number. A temporary number assigned to every polygon in the Census TIGER database. A POLYID is unique only within CENID. Where a TIGER/Line file contains more than one CENID the POLYID may not be unique within that TIGER/Line file. The POLYID is a dynamic number that can change between different versions of the TIGER/Line files. Primary General-Purpose Government A governmental unit that has the ability to provide a variety of public services including activities such as writing general laws and ordinances, providing water, sewer, road maintenance, and other infrastructure maintenance, and issuing bonds. Primary Metropolitan Statistical Area (PMSA) A geographic entity designated by the federal Office of Management and Budget (OMB) for use by federal statistical agencies. If an area met the requirements to qualify as a Metropolitan Statistical Area (MSA) and had a population of one million or more, two or more PMSAs may have been defined within it if statistical criteria were met and local opinion was in favor. A PMSA consisted of a large urbanized county, or a cluster of such counties (cities and towns in New England) that had substantial commuting interchange. When one or more PMSAs were recognized, the balance of the original, larger area became an additional PMSA; the larger area of which they were components then was designated a Consolidated Metropolitan Statistical Area (CMSA). PMSAs were first defined and effective on June 30, 1983. New standards for Core Based Statistical Areas replaced and superseded PMSAs on June 6, 2003. See also Consolidated Metropolitan Statistical Area, metropolitan area, Metropolitan Statistical Area, New England county metropolitan area, and Core Based Statistical Areas. Principal City The largest city of a Core Based Statistical Area, plus additional cities that meet specified statistical criteria. The OMB replaced the term "central city" with the term "principle city" on June 6, 2003. The OMB made this change because the term "central city" had come to connote "inner city" and thus sometimes caused confusion. See also Core Based Statistical Area, Metropolitan Statistical Area, Micropolitan Statistical Area. Public Law Laws of the United States that may be referenced by number, such as PL 94-171 (the 171st law passed by the 94th Congress). Public use microdata area (PUMA) A decennial census geographic entity for which the U.S. Census Bureau provides specially selected extracts of raw data from a small sample of long-form census records that are screened to protect confidentiality of the census records. The extract files are referred to as "public use microdata samples (PUMS)." For Census 2000, state, District of Columbia, and Puerto Rico participants, following U.S. Census Bureau criteria, delineated two types of PUMAs within their states or statistically equivalent entities. PUMAs of one type comprise areas that contain at least 100,000 people. The PUMS files for these PUMAs contain a 5-percent sample of the long-form records. The other type of PUMAs, super-PUMAs, comprise areas of at least 400,000 people. The sample size is 1 percent for the PUMS files for super-PUMAs. PUMAs cannot be in more than one state or statistically equivalent entity. The larger 1-percent PUMAs are aggregations of the smaller 5-percent PUMAs. See also public use microdata sample. Public use microdata sample (PUMS) Files containing records, screened to protect confidentiality, representing 5-percent or 1-percent of the housing units in the United States. Data users can use these files to create their own statistical tabulations and data summaries. See also public use microdata area. PUMA See public use microdata area. PUMS See public use microdata sample. Reach A reach is a continuous, unbroken stretch or expanse of surface water. In the National Hydrography Dataset (NHD), this idea has been expanded to define a reach as a significant segment of surface water that has similar hydrologic characteristics, such as a stretch of stream/river between two confluences, or a lake/pond. Reaches also are defined for unconnected (isolated) features, such as an isolated lake/pond. See also National Hydrography Dataset, reach code. Reach code A reach code is a 14-digit numeric code that uniquely labels each reach in the National Hydrography Dataset (NHD). Each reach code appears only once throughout the Nation. See also National Hydrography Dataset, reach. Real Property Entity A nonfunctioning geographic unit with legal boundaries based on land ownership or realty restrictions rather than being established by general law. Examples include military installations and National Parks that are owned by the federal government or under restricted conveyance. Rubbersheet To rubbersheet is to mathematically shift, stretch, or shrink a portion of a map or image in order to align its coordinates with known control points. Rural All territory, population, and housing units located outside of urbanized areas and urban clusters. Because "urban" and "rural" are delineated independent of any geographic entity except census block, these classifications may cut across all other geographic entities. See also place, urban, urban cluster, urban place, urbanized area. Rural place Any incorporated place or census designated place (CDP) located entirely outside an urbanized area (UA) or urban cluster (UC). See also census designated place, extended place, incorporated place, urban place. School district The territory administered by the elected or appointed authorities of a state, county, tribal, or other local governmental unit to provide educational services to a resident population. See also elementary school district, secondary school district, unified school district. SDAISA See State designated American Indian statistical area. SDTS See Spatial Data Transfer Standard. Secondary county A county that acts as an employment center in combination with a main county or another secondary county within a Core Based Statistical Area (CBSA) that has a core with a population of at least 2.5 million. A secondary county serves as the basis for defining a Metropolitan Division, but only when combined with a main county or another secondary county. See also Core Based Statistical Area, Metropolitan Statistical Area, Metropolitan Division, main county. Secondary school district A school district inclusive of only high school (either the ninth through the twelfth grades or the tenth through the twelfth grades). See also elementary school district, school district, unified district. SF See Summary File. Shape point The non-topological points that describe the position and shape of a chain. Shape points exist only where required. Straight lines require no shape points. SLD See State Legislative District. Spatial Data Transfer Standard Released by the National Institute of Standards and Technology (NIST) as FIPS PUB 173, this standard governs the exchange of geographic information between federal agencies. Specialized or Special-Purpose Government A governmental unit that has the ability to provide a very limited or single-purpose provision of public services such as school districts, water authorities, and so forth. State A primary governmental division of the United States. The U.S. Census Bureau treats the District of Columbia as the equivalent of a state for data presentation purposes. It also treats a number of entities that are not legal divisions of the United States as equivalent to a state for data presentation purposes; for Census 2000, these include Puerto Rico, American Samoa, the Commonwealth of the Northern Mariana Islands, Guam, and the Virgin Islands of the United States. State code A two-digit Federal Information Processing Standard (FIPS) code assigned to identify each state and statistically equivalent entity. The U.S. Census Bureau assigns the codes based on the alphabetic sequence of state names (Puerto Rico, the U.S. Virgin Islands, and the Pacific Island Areas appear at the end); it documents these codes in a FIPS publication (FIPS PUB 5). Also, a two-digit code assigned by the U.S. Census Bureau to identify each state within its census geographic division (Puerto Rico, the Virgin Islands, and the Pacific Island Territories appear at the end). See also Federal Information Processing Standard State Combined Zone See Traffic Analysis Zone. State designated American Indian statistical area (SDAISA) A statistical entity delineated for an American Indian tribe that does not have a land base (reservation) and is recognized as a tribe by a state government, but not the federal government. SDAISAs are identified and delineated for the U.S. Census Bureau by a state liaison identified by the governor's office. SDAISAs generally encompass a compact and contiguous area that contains a concentration of people who identify with a state recognized American Indian tribe and in which there is structured or organized tribal activity. A SDAISA may not be located in more than one state unless the tribe is recognized by both states, and it may not include area within an American Indian reservation, off- reservation trust land, Alaska Native village statistical area (ANVSA), tribal designated statistical area (TDSA), or Oklahoma tribal statistical area (OTSA). The U.S. Census Bureau established SDAISAs as a new geographic statistical area for Census 2000 to differentiate between state recognized tribes without a land base and federally recognized tribes without a land base. State equivalent A type of governmental unit treated by the U.S. Census Bureau as if it were a state for purposes of data presentation. For Census 2000, the state equivalents include the District of Columbia, the Commonwealth of Puerto Rico, the U.S. Virgin Islands, American Samoa, Guam, the Commonwealth of the Northern Mariana Islands, and the U.S. Minor Outlying Islands. See also State. State Legislative District (SLD) Area from which members are elected to state legislatures. The SLDs include the upper (senate) and lower (house) bodies of the state legislature (or for Nebraska, its unicameral legislature). See also legislative district and voting district. Statistical entity A geographic entity that does not have legal boundaries and that is defined solely for the purpose of providing census statistical data. This category includes entities that represent legal administrative units for which the legal boundaries are not used, such as voting districts that are modified to visible features rather than following the legal boundaries and ZIP Code(R) Tabulation Areas that are modified to follow census block boundaries. Some statistical areas consist of entities that serve as a surrogate for a type of legal entity, such as census county divisions and unorganized territories established where legal minor civil divisions either do not exist or lack significant function and census designated places established for concentrations of population that are not legally incorporated as cities, towns, villages, and so forth. Other statistical areas are established only for the provision of census data, such as census tracts and census block groups, that have no legal counterpart. See also legal entity. Statistically equivalent entity A type of geographic entity that, for purposes of data tabulation and presentation, the U.S. Census Bureau treats as the counterpart of a similar type of entity; for example, in Alaska a census area is the statistical equivalent of a county. Subbarrio The primary legal subdivision of a barrio or barrio-pueblo (minor civil division) in 23 municipios in Puerto Rico. See also minor civil division. Sub-MCD See subbarrio. Summary File (SF) One of a series of Census 2000 files containing large amounts of decennial census data for the various levels of the U.S. Census Bureau's geographic hierarchy. Super-PUMA See public use microdata area. Tabulation block A census block used in Census 2000 data products. See also census block, census block number. TAZ See Traffic Analysis Zone. TDSA See Tribal Designated Statistical Area. TIGER(R) Topologically Integrated Geographic Encoding and Referencing. TIGER(R) database A digital (computer-readable) geographic database that automates the mapping and related geographic activities required to sup-port the U.S. Census Bureau's census and survey programs. TLID TIGER/Line Record Identification Number. A permanent identification number that uniquely identifies a complete chain. Topology One component of the science of mathematics dealing with geometric configurations (nodes, complete chains, and polygons) that do not vary when transformed through bending, stretching, or mapping at various scales. Topology explains how points, lines, and areas relate to each other and is used as the foundation for organizing spatial objects in the Census TIGER database. See also geometry, geometry and topology. Town A type of functioning minor civil division (MCD ) in the New England, New York, and Wisconsin; a type of incorporated place in 30 states and the U.S. Virgin Islands. The U.S. Census Bureau treats all towns in New Jersey, Pennsylvania, and South Dakota, and some towns in North Carolina, as the equivalent of an MCD, as well as places, for data presentation purposes. See also county subdivision, dependent place, functioning government, incorporated place, independent place. Township (civil or governmental) A type of functioning minor civil division (MCD) in 12 states, a type of nonfunctioning MCD in 3 states (Arkansas, New Hampshire, and North Carolina), and a type of county subdivision that can be functioning and nonfunctioning in Illinois, Minnesota, and Missouri. (There also are nonfunctioning survey townships in Maine, but these are not recognized by the U.S. Census Bureau for data presentation purposes.) In states where land was subdivided under the public land survey system, many townships correspond to the survey townships. See also county subdivision, functioning government, minor civil division, nonfunctioning entity. Tract See census tract. Traffic analysis zone (TAZ) A special-purpose statistical geographic entity delineated by state and/or local transportation officials for tabulating traffic related data from a decennial census, especially journey-to-work and place-of- work statistics. State Combined Zones, which will be defined by State Department of Transportation (DOTs) officials, will be aggregations of the Metropolitan Planning Organization (MPO) defined TAZs, or where MPOs did not define TAZs, aggregations of census tracts. Tribal block group Under the Census 2000 American Indian/Alaska Native area/Hawaiian home land census geographic hierarchy, a cluster of census blocks within a federally recognized American Indian reservation or off-reservation trust land having the same first digit of their 4-digit census block number. Unlike block groups in the standard census geographic hierarchy, tribal block groups can cross state and county boundaries. See also block group. Tribal census tract Under the Census 2000 American Indian/Alaska Native area/Hawaiian home land census geographic hierarchy, a census tract within a federally recognized American Indian reservation or off-reservation trust land. Tribal census tracts are delineated by tribal governments, or the U.S. Census Bureau where a tribal government declined to participate, for the purpose of presenting decennial census data. Usually containing between 1,000 and 8,000 inhabitants, tribal census tracts generally have boundaries that follow visible features. Unlike census tracts in the standard census geographic hierarchy, tribal census tracts can cross state and county boundaries. See also census tract. Tribal designated statistical area (TDSA) A statistical entity delineated for the U.S. Census Bureau by federally recognized American Indian tribes that do not currently have a legally established land base (reservation or off-reservation trust land). A TDSA generally encompasses a compact and contiguous area that contains a concentration of people who identify with a federally recognized American Indian tribe and in which there is structured or organized tribal activity. A TDSA may be located in more than one state, but it may not include area within an American Indian reservation, off- reservation trust land, Alaska Native village statistical area (ANVSA), or Oklahoma tribal statistical area (OTSA). See also state designated American Indian statistical area. Tribal Government A governmental unit administered by a federally recognized American Indian or Alaska Native tribe. Tribal Subdivision See American Indian tribal subdivision. Trust Land See American Indian trust land. TZID TIGER Zero-Cell ID. A permanent identification number that uniquely identifies a zero-cell (node). UA See urbanized area. UC See urban cluster. UGA See urban growth area. Unified district A school district inclusive of kindergarten through twelfth grade. See also school district. Unincorporated place See census designated place. United States Geological Survey (USGS) The USGS is a bureau of the U.S. Department of the Interior, and is the nation's main topographic mapping agency. United States Postal Service (USPS) An independent corporation of the U.S. Government, the USPS provides mail processing and delivery ser-vices to individuals and businesses in the United States, Puerto Rico, the U.S. Virgin Islands, and the Pacific Island Areas. Unorganized territory (UT) In a state in which the U.S. Census Bureau provides data for minor civil divisions (MCDs), the portion of a county that is not included in a legally established MCD or in an incorporated place that is independent of an MCD. For data presentation purposes, the U.S. Census Bureau recognizes such area as one or more separate county subdivisions, each designated as a UT. For Census 2000, ten states contain one or more UTs. See also county subdivision, census county division, minor civil division. Urban All population, housing units, and territory located within urbanized areas (UAs) and urban clusters (UCs). Because "urban" and "rural" are delineated independent of any other geographic entity, the urban classification may cut across other geographic entities; for example, there is generally both urban and rural territory within both metropolitan and nonmetropolitan areas. See also rural, urban cluster, urban place, urbanized area. Urban Area A collective term used for Census 2000 that refers to both urbanized areas and urban clusters. See also rural, urban, urban cluster, urbanized area. Urban Cluster (UC) An urban cluster (UC) consists of densely settled territory that has at least 2,500 people but fewer than 50,000 people. A UC generally consists of a geographic core of block groups or blocks that have a population density of at least 1,000 people per square mile, and adjacent block groups and blocks with at least 500 people per square mile. It may include less densely settled blocks that form enclaves or indentations, or that connect discontiguous areas that have qualifying densities. The U.S. Census Bureau introduced the UC for Census 2000 to provide a more consistent and accurate measure of the population concentration in and around places. UCs are defined using the same criteria that are used to define UAs for Census 2000. See also rural, urban, urbanized area. Urban growth area (UGA) In Oregon, an "urban growth boundary" is delineated around each incorporated place or a group of incorporated places by state and local officials, and subsequently confirmed in state law, to control urban development. The U.S. Census Bureau refers to the resulting geographic entities as "urban growth areas." UGAs are a new geographic entity for Census 2000. Urban place An incorporated place or census designated place (CDP) inside an urbanized area (UA) or urban cluster (UC). As a result of the UA and UC delineations, a place may be partially within and partially outside of a UA or UC (an extended place). See also extended place, place, rural place, urbanized area. Urbanized area (UA) A UA consists of densely settled territory that contains 50,000 or more people. A UA generally consists of a geographic core of block groups or census blocks that have a population density of at least 1,000 people per square mile, and adjacent block groups and census blocks with at least 500 people per square mile. It may include less densely settled blocks that form enclaves or indentations, or that connect discontiguous areas that have qualifying densities. A UA consists of all or part of one or more incorporated places and/or census designated places (CDPs), and may include additional territory outside of any place. For Census 2000, the UA criteria were extensively revised and the delineations were performed using a zero-based approach. See also urban, urban cluster, urban place. Urban Area code Each urbanized area (UA) and urban cluster (UC) is assigned a 5-digit numeric code, based on a national alphabetical sequence of all urban area names. See also Federal Information Processing Standards. USGS See United States Geological Survey. USPS See United States Postal Service. UT See Unorganized Territory. Village A type of incorporated place in 20 states and American Samoa. The U.S. Census Bureau treats all villages in New Jersey, South Dakota, and Wisconsin, and some villages in Ohio, as the equivalent of a minor civil division (MCD) for data presentation purposes. See also incorporated place, minor civil division, place. Voting district (VTD) Any of a variety of geographic entities, such as precincts, wards, and election districts established by state and local governments for the purpose of conducting elections. VTD See Voting district. ZCTA(TM) See ZIP Code(R) Tabulation Area. ZIP+4(R) A four-digit code that follows a five-digit ZIP Code, established by the U.S. Postal Service (USPS) for the purpose of expediting and auto-mating the delivery of mail. The nine-digit code generally identifies one side of a street segment or an entire cul-de-sac or similar dead-end street. ZIP (Zone Improvement Plan) Code(R) An administrative unit established by the U.S. Postal Service (USPS) for the distribution of mail. It is a five-, seven, nine-, or eleven-digit code assigned by the USPS to a street or portion of a street, a collection of streets, a business or other establishment or structure, or a group of post office boxes to expedite the delivery of mail. ZIP Code(R) Tabulation Area (ZCTA(TM)) A statistical entity developed by the U.S. Census Bureau to approximate the delivery area for a U.S. Postal Service ZIP Code service areas. A ZCTA is an aggregation of one or more census blocks that have the same predominant ZIP Code associated with the mailing addresses in the U.S. Census Bureau's Master Address File. Thus, the Postal Service's delivery areas have been adjusted to encompass whole census blocks. ZCTAs do not include all ZIP Codes used for mail delivery. Zona Urbana In Puerto Rico, a census designated place (CDP) consisting of the municipio seat of government and the adjacent built-up area. A zona urbana cannot extend across its municipio's boundary. See also census designated place, comunidad.