Monthly Estimates of the United States Population Source: Population Estimates Program, Population Division, U.S. Census Bureau Internet Release Date: April 11, 2000 PRINTING THE SUMMARY TABLE Before printing a monthly national population estimate summary table, set the following printing options: Paper Size: Letter (8.5 inches by 11 inches) Orientation: Portrait Left and Right Margins: 1 inch Top and Bottom Margins: 1 inch Font: Courier New, 10 point size These options will ensure that the printed pages match in both width and length with the summary table pages. POPULATION UNIVERSE DEFINITIONS Estimates of the United States resident population include persons resident in the 50 States and the District of Columbia. They exclude residents of the Commonwealth of Puerto Rico, and residents of the outlying areas under United States sovereignty or jurisdiction (principally American Samoa, Guam, Virgin Islands of the United States, and the Commonwealth of the Northern Mariana Islands). The definition of residence conforms to the criterion used in the 1990 census, which defines a resident of a specified area as a person "usually resident" in that area. Estimates of resident population exclude the United States Armed Forces overseas, as well as civilian United States citizens whose usual place of residence is outside the United States. Estimates of the resident population plus Armed Forces overseas include United States residents and members of the Armed Forces on active duty stationed outside the United States, but do not include military dependents and other United States citizens living abroad. Civilian population estimates include United States residents not in the active duty Armed Forces. The difference between resident population plus Armed Forces overseas and civilian population is the worldwide Armed Forces population. This population includes the following groups: regular active duty military personnel as reported in military strength statistics of the five Armed Forces branches in the Departments of Defense and Transportation, reserve forces on three and six months active duty for training, National Guard reserve forces on active duty for four months or more, and students at the military academies. Estimates of the Armed Forces overseas generally include persons reported by their respective branch of the Armed Forces as stationed outside the United States. The Navy overseas estimates include persons ashore at overseas locations, persons located on Naval vessels whose home-ports are outside the United States, and persons located on Naval vessels deployed to the overseas fleets. Estimates of the civilian noninstitutional population differ from the civilian population estimates in that they exclude persons residing in institutions. Such institutions consist primarily of nursing homes, prisons, jails, mental hospitals, and juvenile correctional facilities. While the civilian noninstitutional population has been adopted as the universe for many sample surveys, the current release is not consistent with results of current surveys conducted by the Census Bureau. One such survey is the Current Population Survey, which calibrated its results to 1980-census-based projections through 1993. From 1994 onward, the survey calibrated its results to 1990-census-based projections that have been adjusted for net underenumeration based on the 1990 Post Enumeration Survey. POSTCENSAL ESTIMATION OF RESIDENT POPULATION Estimates of the United States population by 16 categories of sex (male, female), race (White; Black; American Indian, Eskimo, and Aleut; Asian and Pacific Islander), and Hispanic origin (Hispanic, Non-Hispanic) were derived quarterly by updating the resident population enumerated in the 1990 census through the components of population change. The following formula was applied to update each group: (1) 1990 enumeration of resident population, (2) + births to U.S. resident women, (3) - deaths to U.S. residents, (4) + net international migration, (5) + net movement of U.S. Armed Forces and civilian citizens to the United States. For a more detailed discussion of the methods by which these estimates are produced, please consult the documentation files provided with the detailed data files (natdoc.txt). (1) The 1990 enumerated resident population comes from the April 1, 1990 Decennial Census and is not adjusted for the census' net underenumeration. However there is an adjustment for count resolution corrections, as well as adjustment for underenumeration in certain counties and cities that were canvassed in the 1995 test censuses and 1998 dress rehearsals. These corrections were an attempt to bring the population estimates into conformity with changes in the population universe rendered "official" by these activities. (2) Registered births to United States resident women are estimated from data supplied by the National Center for Health Statistics. The primary source for this birth data can be found in the National Center for Health Statistics (NCHS), Monthly Vital Statistics Report, Volume 46, Number 11, Supplement, "Births: Final Data for 1997," and similar publications of NCHS. (3) Registered deaths to United States residents by sex and race are also estimated from data supplied by the National Center for Health Statistics. The primary source for this death data can be found in the National Center for Health Statistics National Vital Statistics Report, Volume 47, Number 19, "Deaths: Final Data for 1997," and similar NCHS publications. (4) The international net migration components are based on a variety of administrative sources and analytic estimates. The Immigration and Naturalization Service supplies data on legal immigrants. The Office of Refugee Resettlement supplies data on persons admitted to the United States as refugees. Puerto Rico immigration and emigration estimates develop from Immigration and Naturalization Service data and independent research conducted by the Census Bureau's International Programs Center. The (presumably small) balance of migration between the United States and other outlying areas under United States jurisdiction is assumed to be zero. Two numerically substantial types of international migration for which reliably accurate and current data are unavailable are undocumented immigration (both in and out of the United States) and the permanent emigration of legal residents. Undocumented immigration refers to the net increase of the undocumented population due to change in residence across the national border by aliens, either by unauthorized entry or by overstaying a temporary (non-immigrant) visa, discounting those that subsequently immigrate legally. For undocumented immigration, we make an allowance of 225,000 net migration per year, which is constant throughout the postcensal estimating period. For emigration of legal residents, we incorporated results of research carried out at the Census Bureau on foreign-born and native-born emigration. For more information about this emigration research, please see Population Division Technical Working Paper #9, "Estimates of the Emigration of the Foreign-Born Population: 1980 to 1990," authored by Bashir Ahmed and David Word, and Population Division Technical Working Paper #10, "Estimation of the Annual Emigration of U.S. Born Persons by Using Foreign Censuses and Selected Administrative Data: Circa 1980," authored by Edward Fernandez. We include an allowance for the net migration of non-refugee temporary residents (most of which are foreign students and scholars) who would be enumerated in the decennial census as residents of the United States. This allowance is intended to preserve the age, sex, race, and Hispanic origin distribution of the population as estimated for the 1990 census date. (5) The temporary movement of federally affiliated United States citizens consists mostly of movement of the active duty Armed Forces and Armed Forces dependents between the United States and overseas. Also included is the movement of civilian federal employees and their dependents. We estimate the migration of federally affiliated citizens by observing trends in the number of personnel abroad, from three sources: a) Armed Forces overseas strength statistics are supplied by the five branches of the Armed Forces in the Departments of Defense (Army, Navy, Marines, and Air Force) and Transportation (Coast Guard). b) The number of military dependents residing overseas is published by the Department of Defense, for four branches of the Armed Forces (excluding Coast Guard). These data come from the Department of Defense, Directorate for Information, Operations, and Reports, "Worldwide Manpower Distribution by Geographic Area." c) The number of civilian Federal employees overseas is supplied by the Office of Personnel Management. This number is inflated to include dependents. These data come from the United States Office of Personnel Management, Federal Civilian Workforce Statistics, "Employment and Trends" series. The inference of net migration from this population to the United States follows a reverse component-of-change logic applied to the federally affiliated overseas population. The net increase in the overseas federal population, minus net recruits to this population from abroad (for example, residents of outlying areas joining the Armed Forces), minus births, plus deaths, provides an estimate of the net migration to the overseas federal population from the United States. The negative of this estimate is the estimated migration of federally affiliated citizens to the United States from overseas. The net migration of United States citizens not affiliated with the federal government, as well as the temporary movement of students, scholars, and embassy personnel, are tacitly assumed to be zero, although these movements do, in fact, represent a change of residence in and out of the United States according to the residence definition used in the estimates. INTERCENSAL ESTIMATES OF THE RESIDENT POPULATION, BY AGE, SEX, RACE, AND HISPANIC ORIGIN Intercensal estimates, in this case estimates from April 1, 1980, to April 1, 1990, are different in their interpretation than postcensal estimates (from April 1, 1990 forward), primarily because population change is measured from the difference between two census enumerations, rather than through administrative data on the components of change. They can be derived from 1980-census-based postcensal estimates through a process of distributing the error of closure - that portion of the total change from the 1980 to the 1990 census not measured by administrative data on change - into time intervals within the intercensal period. The method is described in detail in Current Population Reports, Series P25, Number 1095, "U.S. Population Estimates, by Age, Sex, Race, and Hispanic Origin: 1980 to 1991," page xvii. ESTIMATION OF RESIDENT POPULATION PLUS ARMED FORCES OVERSEAS, CIVILIAN POPULATION, AND CIVILIAN NONINSTITUTIONAL POPULATION To produce the resident population plus Armed Forces overseas, we simply added the Armed Forces overseas to the resident population. Armed Forces overseas is estimated directly from monthly data on active duty military by duty location, supplied by the five branches of the Armed Forces, although it is necessary to impute the monthly number of Naval personnel on board ships whose home-ports are outside the United States or deployed to the overseas fleets from annual data supplied by the Navy. Civilian population is the difference obtained by subtracting worldwide Armed Forces strength, obtained from the same sources, from resident population plus Armed Forces overseas. Civilian noninstitutional population results from subtracting the institutional population, as developed within the Census Bureau's Population Division with data from state demography contacts, from the civilian population. NOTES Population estimates are subject to revision, as revised input data become available. These revisions normally occur once a year in the spring. The most recent estimate date shown here will be subject to monthly update. All Population Division publications may be obtained by writing to Population Division, U.S. Bureau of the Census, Washington, D.C. 20233; calling the Statistical Information Staff at (301)457-2422; or by e-mailing a message to POP@CENSUS.GOV (please include telephone number).