Population coverage. The population in this report includes the civilian population of the United States and members of the Armed Forces in the United States living off base or with their families on base, but excludes all other members of the Armed Forces. Inmates of institutions were not included in the survey.

Geographic regions. The four major regions of the United States for which data are presented in this report represent groups of States, as follows:

New

Northeast: Connecticut, Maine, Massachusetts, Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont;

North Central: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, Wisconsin;

South: Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, West Virginia;

West: Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, Wyoming.

Mobility status. The population 5 years old and over was classified according to mobility status on the basis of a comparison between the place of residence of each individual at the time of the March 1980 survey and the place of residence 5 years earlier. Nonmovers are all persons who were living in the same house at the end of the period as at the beginning of the period. Movers are all persons who were living in a different house at the end of the period than at the beginning. Movers are further classified as to whether they were living in the same county, State, or region; were movers from abroad; were living in the same or different central city or SMSA; or had made some other type of move.

Metropolitan residence. The population residing in standard metropolitan statistical areas (SMSA's) constitutes the metropolitan population. Except in New England, an SMSA is a county or group of contiguous counties which contains at least one city of 50,000 inhabitants or more, or "twin cities" with a combined population of at least 50,000. In addition to the county or counties containing this "central city," contiguous counties are included in an SMSA if, according to certain criteria, they are essentially metropolitan in character

and are socially and economically integrated with the central county. In New England, SMSA's consist of towns and cities, rather than counties. The metropolitan population in this report is based on SMSA's defined in the 1970 census and does not include any subsequent additions or changes. The terms "nonmetropolitan" and "outside SMSA's" are synonymous. The "balance of the SMSA" refers to the remainder of the SMSA outside the central city or cities, and is synonymous with the term "suburbs." The "size of the SMSA" refers to the number of persons living in the SMSA at the time of the 1970 census.

Age. This classification is based on the age of the person at his or her last birthday.

Race. The population is divided into three groups on the basis of race: White, Black, and other races. The last category includes Indians, Japanese, Chinese, and any other race except White and Black. In this report, other races are included in the totals but not shown separately.

Spanish origin. Persons of Spanish origin were determined on the basis of a question that asked for self-identification of the person's origin or descent. Respondents were asked to select their origin (or the origin of some other household member) from a "flash card" listing ethnic origins. Persons of Spanish origin, in particular, were those who indicated that their origin was Mexican, Puerto Rican, Cuban, Central or South American, or some other Spanish origin. Persons of Spanish origin may be of any race.

Marital status. The marital status classification identifies four major categories: single, married, widowed, and divorced. These terms refer to the marital status at the time of the survey. Married persons are further divided into "married, spouse present" and "married, spouse absent." A person was classified as "married, spouse present" if the husband or wife was reported as a member of the household, even though he or she may have been temporarily residing elsewhere.

Household. A household consists of all the persons who occupy a housing unit. A house, an apartment or other group of rooms, or a single room, is regarded as a housing unit when it is occupied or intended for occupancy as separate living quarters; that is, when the occupants do not live and eat with any other persons in the structure and there is either (1) direct access from the outside or through a common hall or (2) a kitchen or cooking equipment for the exclusive use

of the occupants. 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 in a housing unit, or a group of unrelated persons sharing a housing unit as partners, is also counted as a household. Persons living in rooming houses, college dormitories, or other group quarters are not included in the count as households.

Householder. The householder refers to the person (or one of the persons) in whose name the housing unit is owned or rented (maintained) or, if there is no such person, any adult member, excluding roomers, boarders, or paid employees. If the house is owned or rented jointly by a married couple, the householder may be either the husband or the wife. The person designated as the householder is the "reference person" to whom the relationship of all other household members, if any, is recorded. Prior to 1980, the husband was always considered the household head (householder) in married-couple households. The number of householders is equal to the number of households. Also, the number of family householders is equal to the number of families.

Family. A family is a group of two or more persons (one of whom is the householder) related by birth, marriage, or adoption and residing together; all such persons (including related subfamily members) are considered as members of one family. Beginning with the 1980 CPS, unrelated subfamilies (referred to in the past as secondary families) are no longer included in the count of families, nor are the members of unrelated subfamilies included in the count of family members.

Married couple. A married couple, as defined for census purposes, is a husband and wife enumerated as members of the same household. The married couple may or may not have children living with them. The expression "marriedcouple" before the term "household" or "family" indicates that the household or family is maintained by a husband and wife.

Related persons and family members. In the classification of households by number of related persons, the person or couple who maintains the household (or housing unit) and all persons in the household related to them are included. In the classification of families by number of family members, all persons in the family are included. The number of family members is the same as the size of the family.

Nonfamily householder. A nonfamily householder (formerly called a primary individual) is a person maintaining a household while living alone or with nonrelatives only.

Own children. "Own children" in a family are sons and daughters, including stepchildren and adopted children, of the family householder. The count of own children under 18 years old is limited to single (never married) children.

Years of school completed. Data on years of school

questions concerning the highest grade of school attended by the person and whether or not the grade was finished. The questions on educational attainment apply only to schooling that may advance a person toward an elementary school certificate or high school diploma, or a college, university, or professional school degree.

Labor force status. Persons are classified as "in the labor force" if they were employed as civilians, unemployed, or in the Armed Forces during the survey week. The "civilian labor force" is comprised of all civilians classified as employed or unemployed. All civilians who are not classified as employed or unemployed are defined as "not in labor force." Employed persons include all civilians who did any work at all during the specified week as paid employees or in their own business or professional practice, or on their own farm, or who worked 15 hours or more as unpaid workers on a farm or in a business operated by a member of the family, and all those who were not working but who had a job or business from which they were temporarily absent, whether or not they were paid by their employers for the time off, and whether or not they were seeking other jobs. Excluded from the employed group are persons whose only activity consisted of work in or around their own house or volunteer work. Unemployed persons are those civilians who had no employment but were available for work and had engaged in any specific jobseeking activity within the last 4 weeks or were on a union or professional register, were waiting to be called back to a job from which they had been laid off, or were waiting to report to a new job within 30 days.

Occupation. The data on occupation of employed persons refer to the civilian job held during the survey week. Persons employed at two or more jobs were reported in the job at which they worked the greatest number of hours during the week. The occupation groupings used here are mainly the major groups used in the 1970 census. The composition of these groups is shown in the 1970 Census of Population, PC(1)-C Series, General Social and Economic Characteristics.

Income. For each person 14 years old and over, questions were asked on the amount of money income received in the preceding calendar year. The income of the family does not include amounts received by persons who were members of the family during all or part of the income year if these persons no longer resided with the family at the time of the survey. On the other hand, family income includes amounts reported by related persons who did not reside with the family during the income year but were members of the family on the survey date.

Public assistance. Families are classified as "with public assistance" if one or more persons in the family received any public assistance or welfare payments in the preceeding year. "Public assistance," as defined in this report, does not include Supplemental Security Income (SSI) payments.

Poverty status. Families and unrelated individuals are classi

poverty index adopted by a Federal Interagency Committee

in 1969. This index provides a range of income cutoffs or "poverty thresholds" adjusted to take into account such factors as family size, sex and age of the family householder, the number of children, and farm-nonfarm residence. These income cutoffs are updated every year to reflect the changes in the Consumer Price Index. The average poverty threshold for a nonfarm family of four was $8,414 in 1980.

Mean. The mean (average) number of persons per family is the value obtained by dividing the number of persons having the characteristics under consideration by the appropriate number of families. The mean number of own children is the number of own children of the age under consideration divided by the total number of families with own children.

Median. The median is the value which divides the distribution into two equal parts, one-half of the cases falling below this value and one-half of the cases exceeding this value. It is presented in connection with the data on age, years of school completed, and income.

Rounding. Detailed data in the tables may not agree with the totals because of independent rounding. Furthermore, calculations such as means, medians, and percentages are based on the unrounded figures and therefore may not agree with those derived from rounded figures in the table.

Symbols. A dash (-) represents zero or rounds to zero and the symbol "B" means that the base is less than 75,000.