This section presents statistics on the growth, distribution, and characteristics of the U.S. population. The principal source of these data is the U.S. Census Bureau, which conducts a decennial census of population, a monthly population survey, a program of population estimates and projections, and a number of other periodic surveys relating to population characteristics. For a list of relevant publications, see the Guide to Sources of Statistics in Appendix I.
Decennial censuses-The U.S. Constitution provides for a census of the population every 10 years, primarily to establish a basis for apportionment of members ofthe House of Representatives among the states. For over a century after the first census in 1790, the census organization was a temporary one, created only for each decennial census. In 1902, the Census Bureau was established as a permanent federal agency, responsible for enumerating the population and also for compiling statistics on other population and housing characteristics.
Historically, the enumeration of the population has been a complete count. That is, an attempt is made to account for every person, for each person’s residence, and for other characteristics (sex, age, family relationships, etc.). Since the 1940 census, in addition to the complete count information, some data have been obtained from representative samples of the population. In the 1990 and 2000 censuses, variable sampling rates were employed. For most of the country, 1 in every 6 households (about 17 percent) received the long form or sample questionnaire; in governmental units estimated to have fewer than 2,500 inhabitants, every other household (50 percent) received the sample questionnaire to enhance the reliability of sample data for small areas. Exact agreement is not to be expected between sample data and the 100-percent count. Sample data may be used with confidence where large numbers are involved and assumed to indicate trends and relationships where small numbers are involved.
Current Population Survey (CPS)-Thisis a monthly nationwide survey of a scientifically selected sample representing the noninstitutional civilian population. The sample is located in 754 areas with coverage in every state and the District of Columbia and is subject to sampling error. At the present time, about 60,000 occupied households are eligible for interview every month; of these between 6 and 7 percent are, for various reasons, unavailable for interview.
While the primary purpose of the CPS is to obtain monthly statistics on the labor force, it also serves as a vehicle for inquiries on other subjects. Using CPS data, the Bureau issues a series of publications under the general title of Current Population Reports, which cover population characteristics (P20), consumer income (P60), special studies (P23), and other topics.
Estimates of population characteristics based on the CPS will not agree with the counts from the census because the CPS and the census use different procedures for collecting and processing the data for racial groups, the Hispanic population, and other topics. Caution should also be used when comparing estimates for various years because of the periodic introduction of changes into the CPS. Beginning in January 1994, a number of changes were introduced into the CPS that effect all data comparisons with prior years. These changes include the results of a major redesign of the survey questionnaire and collection methodology and the introduction of 1990 census population controls, adjusted for the estimated undercount. Beginning with the 2001 CPS Annual Demographic Supplement the independent estimates used as control totals for the CPS are based on civilian population benchmarks consistent with Census 2000. In March 2002, the sample size of the Annual Demographic Supplement was increased to approximately 78,000. These changes in population controls had relatively little impact on derived measures such as means, medians, and percent distribution, but did have a significant impact on levels.
Population estimates and projections -Estimates of the United States population are derived by updating the resident population enumerated in Census 2000 with information on the components of population change: births, deaths, and net international migration. The April 1, 2000, population used in these estimates reflects modifications to the Census 2000 population as documented in the Count Question Resolution program.
Registered births and deaths are estimated from data supplied by the National Center for Health Statistics. The net international migration component in the population estimates includes: legal immigration to the United States, emigration of foreign born and native people from the United States, net movement between the United States and Puerto Rico, estimates of temporary migrants, and estimates of net residual foreign-born population, which include unauthorized migration.
For the first time, the estimates of the international migration component incorporated data available from the Census 2000 Supplementary Survey (C2SS) and the 2001 Supplementary Survey (SS01) along with estimates developed from the Demographic Analysis and Population Estimates (DAPE) project (See Deardorff and Blumerman, 2001, ‘‘Evaluation Components of International Migration: Estimates of the Foreign-Born Population by Migrant Status in 2000,’’ Population Division Working Paper Series, No. 58).
Estimates for states and counties areas are based on the same components of change data and sources as the national estimates with the addition of net internal migration. School enrollment statistics from state departments of education and parochial school systems, federal income tax returns from the Internal Revenue Service, group quarters data from the Federal-State Cooperative Program, and medicare data from the Centers of Medicare and Medicaid Services are also included.
The population by age for April 1, 1990, (shown in Table 11) reflects modifications to the 1990 census data counts. The review of detailed 1990 information indicated that respondents tended to report age as of the date of completion of the questionnaire, not as of April 1, 1990. In addition, there may have been a tendency for respondents to round up their age if they were close to having a birthday. A detailed explanation of the age modification procedure appears in 1990 Census of Population and Housing, Data Paper Listing CPH-L74.
Population estimates and projections are available on the Census Bureau Internet site <http://www.census.gov/>. These estimates and projections are consistent with official decennial census figures with no adjustment for estimated net census coverage. However, the categories for these estimates and projections by race have been modified and are not comparable to the census race categories (see section below under ‘‘Race’’). For details on methodology, see the sources cited below the individual tables.
Immigration-Immigration (migration toa country) is one component of international migration; the other component is emigration (migration from a country). Inits simplest form, international migration is defined as any movement across a national border. In the United States, federal statistics on international migration are produced primarily by the U.S. Census Bureau and the Bureau of Citizenship and Immigration Services (located in the Department of Homeland Security). The U.S. Bureau of Citizenship and Immigration Services was formerly the Immigration and Naturalization Service.
The Census Bureau collects international migration data through its decennial censuses and numerous surveys of the U.S. population. The Bureau of Citizenship and Immigration Services publishes immigration data in the Yearbook of Immigration Statistics and collects these data from several administrative records such as the Immigrant Visa and Alien Registration (OF-155, U.S. State Department) for new arrivals, and the Memorandum of Creation of Record of Lawful Permanent Residence (I-181, INS) for persons adjusting migrant status. Immigrants are aliens admitted for legal permanent residence in the United States. The category, immigrant, includes persons who may have entered the United States as nonimmigrants or refugees, but who subsequently changed their status to that of a permanent resident. Nonresident aliens admitted to the United States for a temporary period are nonimmigrants. Refugees are considered nonimmigrants when initially admitted into the United States but are not included in nonimmigrant admission data. A refugee is an alien outside the United States who is unable or unwilling to return to his or her country of nationality because of persecution or a well-founded fear of persecution.
U.S. immigration law gives preferential immigration status to persons with a close family relationship with a U.S. citizen or legal permanent resident, persons with needed job skills, or persons who qualify as refugees. Immigration to the United States can be divided into two general categories: (1) those subject to the annual worldwide limitation and (2) those exempt from it. Numerical limits are imposed on visas issued and not on admissions. The maximum number of visas allowed to be issued under the preference categories in 2001 was 418,074- 226,000 for family-sponsored immigrants and 192,074 for employment-based immigrants. There are nine categories among which the family-sponsored and employment-based immigrant visas are distributed, beginning in fiscal year 1992. Within the overall limitations the percountry limit for independent countries is set to 7 percent of the total family sponsored and employment-based limits, while dependent areas are limited to 2 percent of the total. The 2001 limit allowed no more than 29,265 preference visas for any independent country and 8,361 for any dependency. Those exempt from the worldwide limitation include immediate relatives of U.S. citizens, refugees and asylees adjusting to permanent residence, and other various classes of special immigrants (see Table 6).
The Refugee Act of 1980 provides for a uniform admission procedure for refugees of all countries, based on the United Nations’ definition of refugees. Authorized admission ceilings are set annually by the President in consultation with Congress. After 1 year of residence in the United States, refugees are eligible for immigrant status.
Metropolitan Areas-The United States Office of Management and Budget (OMB) defines metropolitan and micropolitan statistical areas according to published standards that are applied to Census Bureau data. The general concept of a metropolitan or micropolitan statistical area is that of a core area containing a substantial population nucleus, together with adjacent communities having a high degree of economic and social integration with that core. Currently defined metropolitan and micropolitan statistical areas are based on application of 2000 standards to 2000 decennial census data. The term ‘‘metropolitan area’’ (MA) was adopted in 1990 and referred collectively to metropolitan statistical areas (MSAs), consolidated metropolitan statistical areas (CMSAs), and primary metropolitan statistical areas (PMSAs). The term ‘‘core based statistical area’’ (CBSA) became effective in 2000 and refers collectively to metropolitan and micropolitan statistical areas.
Over time, new statistical areas are created and the components of others change. Because of historical changes in geographic definitions, users must be cautious in comparing data for these statistical areas from different dates. For some purposes, comparisons of data for areas as defined at given dates may be appropriate; for other purposes, it may be preferable to maintain consistent area definitions. For descriptive details and a listing of titles and components of metropolitan and micropolitan areas, see Appendix II.
Urban and rural-For Census 2000, the Census Bureau classified as urban all territory, population, and housing units located within urbanized areas (UAs) and urban clusters (UCs). A UA consists of densely settled territory that contains 50,000 or more people, while a UC consists of densely settled territory with at least 2,500 people but fewer than 50,000 people. (UCs are a new type of geographic entity for Census 2000.) Prior to Census 2000-from the 1950 census through the 1990 census-the urban population consisted of all people living in UAs and most places outside of UAs with a census population of 2,500 or more.
UAs and UCs encompass territory that generally consists of: Population 3 U.S. Census Bureau, Statistical Abstract of the United States: 2003
• A cluster of one or more block groups or census blocks each of which has a population density of at least 1,000 people per square mile at the time.
• Surrounding block groups and census blocks each of which has a population density of at least 500 people per square mile at the time.
• Less densely settled blocks that form enclaves or indentations, or are used to connect discontiguous areas with qualifying densities.
They also may include an airport located adjacent to qualifying densely settled area if it has an annual enplanement (aircraft boarding) of at least 10,000 people.
‘‘Rural’’ for Census 2000 consists of all territory, population, and housing units located outside of UAs and UCs. Prior to Census 2000, rural consisted of all territory, population, and housing outside of UAs and outside of other places designated as ‘‘urban.’’ For Census 2000, many more geographic entities, including metropolitan areas, counties, county subdivisions, and places, contain both urban and rural territory, population, and housing units.
Residence-In determining residence, the Census Bureau counts each person as an inhabitant of a usual place of residence (i.e., the place where one usually lives and sleeps). While this place is not necessarily a person’s legal residence or voting residence, the use of these different bases of classification would produce the same results in the vast majority of cases.
Race-For the 1990 census, the Census Bureau collected and published racial statistics as outlined in Statistical Policy Directive No. 15 issued by the U.S. Office of Management and Budget (OMB). This directive provided standards on ethnic and racial categories for statistical reporting to be used by all federal agencies. According to the directive, the basic racial categories were American Indian or Alaskan Native, Asian or Pacific Islander, Black, and White. (The directive identified Hispanic origin as an ethnicity.) The question on race for Census 2000 was different from the one for the 1990 census in several ways. Most significantly, respondents were given the option of selecting one or more race categories to indicate their racial identities. Because of these changes, the Census 2000 data on race are not directly comparable with data from the 1990 census or earlier censuses. Caution must be used when interpreting changes in the racial composition of the U.S. population over time. Census 2000 adheres to the federal standards for collecting and presenting data on race and Hispanic origin as established by OMB in October 1997. Starting with Census 2000, the OMB requires federal agencies to use a minimum of five race categories: White, Black or African American, American Indian or Alaska Native, Asian, and Native Hawaiian or Other Pacific Islander. For respondents unable to identify with any of these five race categories, OMB approved and included a sixth category- ‘‘Some other race’’ on the Census 2000 questionnaire. The Census 2000 question on race included 15 separate response categories and three areas where respondents could write in a more specific race group. The response categories and write-in answers can be combined to create the five minimum OMB race categories plus ‘‘Some other race.’’ People who responded to the question on race by indicating only one race are referred to as the race alone population, or the group that reported only one race category. Six categories make up this population: White alone, Black or African American alone, American Indian and Alaska Native alone, Asian alone, Native Hawaiian and Other Pacific Island alone, and Some other race alone. Individuals who chose more than one of the six race categories are referred to as the Two or more races population,or as the group that reported more than one race. Additionally, respondents who reported one race together with those who reported the same race plus one or more other races are combined to create the race alone or in combination categories.For example, the White alone or in combination group consists of those respondents who reported White combined with one or more other race groups, such as ‘‘White and Black or African American,’’ or ‘‘White and Asian and American Indian and Alaska Native.’’ Another way to think of the group who reported White alone or in combination is as the total number of people who identified entirely or partially as White. This group is also described as people who reported White, whether or not they reported any other race.
The alone or in combination categoriesare tallies of responses rather than respondents. That is, the alone or in combination categories are not mutually exclusive. Individuals who reported two races were counted in two separate and distinct alone or in combination race categories, while those who reported three races were counted in three categories, and so on. Consequently, the sum of all alone or in combination categories equalsthe number of races reported (i.e., responses) which exceeds the total population.
The concept of race, as used by the Census Bureau, reflects self-identification by people according to the race or races with which they most closely identify. These categories are sociopolitical constructs and should not be interpreted as being scientific or anthropological in nature. Furthermore, the race categories include both racial and national-origin groups.
Data for the population by race for April 1, 2000, (shown in Table 13) are modified counts and are not comparable to Census 2000 race categories. These numbers were computed using Census 2000 data by race that had been modified to be consistent with the 1997 Office of Management and Budget’s, ‘‘Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity,’’ (Federal Register Notice, Vol. 62, No 210, October 1997). A detailed explanation of the race modification procedure appears on the Census Web page, <http://www.census.gov/popest/national/>.
In the CPS and other household sample surveys in which data are obtained through personal interview, respondents are asked to classify their race as: (1) White; (2) Black, African American or Negro; (3) American Indian or Alaska Native; (4) Asian; (5) Native Hawaiian or Other Pacific Islander. Beginning January 2003, respondents were allowed to report more than one race to indicated their mixed racial heritage.
Hispanic population-The Census Bureau collected data on the Hispanic origin population in the 2000 census by using a self-identification question. Persons of Spanish/Hispanic origin are those who classified themselves in one of the specific Hispanic origin categories listed on the questionnaire- Mexican, Puerto Rican, Cuban, as well as those who indicated that they were of Other Spanish/ Hispanic origin. Persons of Other Spanish/ Hispanic origin are those whose origins are from Spain, the Spanish-speaking countries of Central or South America, or the Dominican Republic.
In the CPS information on Hispanic persons is gathered by using a selfidentification question. Persons classify themselves in one of the Hispanic categories in response to the question: ’’What is the origin or descent of each person in this household?’’ Hispanic persons in the CPS are persons who report themselves as Mexican-American, Chicano, Mexican, Puerto Rican, Cuban, Central or South American (Spanish countries), or other Hispanic origin.
Traditional and current data collection and classification treat race and Hispanic origin as two separate and distinct concepts in accordance with guidelines from the OMB. Race and Hispanic origin are two separate concepts in the federal statistical system. People who are Hispanic may be of any race and people in each race group may be either Hispanic or Not Hispanic. Also, each person has two attributes, their race (or races) and whether or not they are Hispanic. The overlap of race and Hispanic origin is the main comparability issue. For example, Black Hispanics (Hispanic Blacks) are included in both the number of Blacks and in the number of Hispanics. For further information, see Census Web page, <http://www.census.gov/population/www/socdemo/compraceho.html>.
Foreign-born and native populations -The Census Bureau separates the U.S. resident population into two groups based on whether or not a person was a U.S. citizen at the time of birth. Anyone born in the United States or a U.S. Island Area (such as Puerto Rico) or born abroad to a U.S. citizen parent is a U.S. citizen at the time of birth and consequently included in the native population. Theterm foreign-born population refers toanyone who is not a U.S. citizen at birth. This includes naturalized U.S. citizens, legal permanent resident aliens (immigrants), temporary migrants (such as students), humanitarian migrants (such as refugees), and people illegally present in the United States. The Census Bureau provides a variety of demographic, social, economic, geographic, and housing information on the foreign-born population in the United States. More information on the foreign-born population collected from censuses and surveys is available at the Foreign-Born Population page, <http://WWW.CENSUS.GOV/population/www/socdemo/foreign.html>.
Mobility status-The U.S. population is classified according to mobility status on the basis of a comparison between the place of residence of each individual at the time of the survey or census and the place of residence at a specified earlier date. Nonmovers are all persons who were living in the same house or apartment at the end of the period as at the beginning of the period. Movers are all persons who were living in a different house or apartment at the end of the period than at the beginning of the period. Movers are further classified as to whether they were living in the same or different county, state, or region or were movers from abroad. Movers from abroad include all persons, either U.S. citizens or noncitizens, whose place of residence was outside the United States at the beginning of the period; that is, in Puerto Rico, another U.S. Island Area, or a foreign country.
Living arrangements-Living arrangements refer to residency in households or in group quarters. A ’’household’’ comprises all persons who occupy a ’’housing unit,’’ that is, a house, an apartment or other group of rooms, or a single room that constitutes ’’separate living quarters.’’ A household includes the related family members and all the unrelated persons, if any, such as lodgers, foster children, wards, or employees who share the housing unit. A person living alone or a group of unrelated persons sharing the same housing unit is also counted as a household. See text, Section 20, Construction and Housing, for definition of housing unit.
All persons not living in housing units are classified as living in group quarters. These individuals may be institutionalized, e.g., under care or custody in juvenile facilities, jails, correctional centers, hospitals, or nursing homes; or they may be residents in noninstitutional group quarters such as college dormitories, group homes, or military barracks.
Householder-The householder is the first adult household member listed on the questionnaire. The instructions call for listing first the person (or one of the persons) in whose name the home is owned or rented. If a home is owned or rented jointly by a married couple, either the husband or the wife may be listed first. Prior to 1980, the husband was always considered the householder in married-couple households. Family-The term family refers to a group of two or more persons related by birth, marriage, or adoption and residing together in a household. A family includes among its members the householder.
Subfamily-A subfamily consists of a married couple and their children, if any, or one parent with one or more nevermarriedchildren under 18 years old living in a household. Subfamilies are divided into ’’related’’ and ’’unrelated’’ subfamilies. A related subfamily is related to, but does not include, the householder. Members of a related subfamily are also members of the family with whom they live. The number of related subfamilies, therefore, is not included in the count of families. An unrelated subfamily may include persons such as guests, lodgers, or resident employees and their spouses and/or children; none of whom is related to the householder.
Married couple-A married couple is defined as a husband and wife living together in the same household, with or without children and other relatives.
Statistical reliability-For a discussion of statistical collection and estimation, sampling procedures, and measures of statistical reliability applicable to Census Bureau data, see Appendix III.