Resident Population Estimates of the United States by Age and Sex 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. RESIDENT POPULATION UNIVERSE DEFINITION 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. 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 Rican 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. ESTIMATION OF THE POPULATION BY AGE AND SEX A. The 1990 Census Base Population While the 1990 Decennial Census defines most of the base population for these estimates, the total resident population for April 1, 1990 (248,790,925) does not agree with the 1990 census figure as originally published (248,709,873). The difference, as reflected throughout the entire postcensal estimates series, arises from the sources described above: count resolution corrections and various local adjustments for underenumeration resulting from the 1995 test censuses and the 1998 census dress rehearsals. Respondent's age was reported on the 1990 census questionnaire; however, the age distribution shown in these estimates differs with the distribution shown in the 1990 census publications. Such modifications brought the definition of age into conformity with definitions used for data from other sources, such as vital statistics. The aim was to correct biases in census age tabulations that resulted from displacement of age reporting from the reference date of the census. In 1990 census publications, age is based on respondents' direct reports of age at last birthday, with some editing for age misstatement. This definition proved inadequate for postcensal estimates, as it was apparent that many respondents reported their age (even if reported correctly) at the time of completion of the census form or interview by an enumerator, either of which could have occurred several months after the April 1 reference date. As a result, age was biased upward. Modification was based on a re-specification of age, for most individual respondents, according to their year of birth. Age was derived from year of birth by allocating date of birth to the first quarter and last three quarters of each year, subtracting year of birth from 1990 for those born before April 1, and from 1989 for those born after April 1. The allocation was based on a historical series of registered births by month. B. Updating the Population by Age The base population is aged one year for each year passed, from the census base date to the estimate reference date. For each year, births during the year form the new population aged under 1. Distributions of deaths by age at death (including infants) are converted to deaths decedent's age as of each estimate date, and subtracted from the updated population age distribution. Net international migration and the net migration of United States citizens by age are similarly adapted to year of birth, and added to the updated population. C. The "Inflation-Deflation" Method Once the postcensal population estimates by sex, race, and Hispanic origin are computed, the age distribution of each sex-race-Hispanic category is estimated by the inflation-deflation method. This method seeks to allow each age group in the census base population to advance one year of age for each year after the census, reflecting the effects of births, deaths and migration, while preserving - without aging - the age pattern of census undercoverage estimated for the base population. Were this method not used, the disturbance of the age distribution caused by the underenumeration would effectively grow older, rendering age categories inconsistent over time. 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," pp. xvii-xviii. 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).