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Geographic Areas
"Geography" is a collective term referring to the types of geographic areas used by the Census Bureau in its
data collection and tabulation operations, including their structure, designations, and relationships to one another.
A geography can be a geographic unit of any type, legal or statistical, such as a state, county, place, county subdivision,
census tract, or census block.
Several geographic levels are available in the 2005 ACS Special Product for the Gulf Coast Area:
1) entire state,
2) FEMA-designated IPA area of the state,
3) balance of the state,
4) Metropolitan Statistical Areas,
5) groupings of counties and parishes, and
6) individual counties and parishes.
Entire State
The estimates for the entire state include all data collected from all counties throughout the state for the January
through August 2005 time period and the September through December 2005 time period.
FEMA-designated IPA Area of the State
The FEMA-designated IPA area of the state is the sum of all the counties in the state that were designated by
FEMA as counties receiving individual and public assistance. For example, the state of Louisiana has 37 parishes
that were identified as FEMA-designated IPA counties. The estimate for this level of geography displays all of those
affected counties as a single entity, i.e., the sum of the FEMA-designated IPA area in Louisiana.
Balance of the State
The balance of the state consists of the remaining counties in a state that were not FEMA-designated IPA counties.
For example, Texas has a total of 254 counties. Twenty-two of those counties were designated as IPA counties.
The 232 remaining counties comprise the balance of the state for Texas.
Metropolitan Statistical Areas
The U.S. Office of Management and Budget defines metropolitan statistical areas for purposes of collecting, tabulating,
and publishing Federal statistical data. A metropolitan statistical area is composed of one or more whole counties or
equivalent entities and contains at least one urbanized area of 50,000 or more population, plus adjacent territory that
has a high degree of social and economic integration with the core as measured by commuting. For example, the New
Orleans-Metairie-Kenner, Louisiana Metropolitan Statistical Area includes the parishes of Jefferson, Orleans,
Plaquemines, St. Bernard, St. Charles, St. John the Baptist, and St. Tammany.
Groupings of Counties and Parishes
Groupings of counties exist for several reasons. To ensure that individual responses are kept confidential,
ACS estimates have not been released in counties with an insufficient number of interviews in the September through
December 2005 period. Counties with an insufficient number of interviews were combined with surrounding counties to
form a single geography.
For example, Hale County in Alabama did not meet the minimum threshold of interviewed persons required for the
production of estimates specific to Hale County. Therefore, the data for Hale County are published along with data from
Greene, Pickens, and Sumter Counties in Alabama. The data for the area representing these counties are distinguished as
"Greene/Hale/Pickens/Sumter, AL." Looking at a map, these four counties are geographically grouped together.
Geographically, it would also make sense to include Tuscaloosa County in this group; however, Tuscaloosa County met the
minimum threshold of interviewed persons so data specific to Tuscaloosa County alone have been published. Census Bureau
staff worked closely with local officials in forming these county groupings.
In many cases, counties were grouped together because local officials indicated that having single estimates for
identified county groupings would be useful. These groupings include Planning and Development Districts (PDDs),
Labor Market Areas, and other established local entities. For example, Hinds County in Mississippi met the minimum
threshold of interviewed persons required for county-specific estimates. It is also included in the Central PDD, along
with Copiah, Madison, Rankin, Simpson, Warren, and Yazoo Counties, as identified by officials in the state of
Mississippi.
Individual Counties and Parishes
Data have been published for many individual counties and parishes. In order for a county to have published data
exclusive to itself, a minimum number of interviews must have been conducted in that county during the last four months
of 2005. This threshold was established to ensure the integrity and quality of the data as well as to protect the
confidentiality of the respondents.
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