URBANIZED AREAS

As indicated above, one of the components of urban territory under the new definition of urban-rural residence is the urban fringe. Areas of this type in combination with the cities which they surround have been defined in the 1950 Census as urbanized

areas.

Each urbanized area contains at least one city with 50,000 inhabitants or more in 1940 or according to a special census taken since 1940. Each urbanized area also includes the surrounding closely settled incorporated places and unincorporated areas that comprise its urban fringe. The boundaries of these fringe areas were established to conform as nearly as possible to the actual boundaries of thickly settled territory, usually characterized by a closely spaced street pattern. The territory of an urbanized area may be classified into incorporated parts and unincorporated parts. (See urbanized area maps which follow table 9 in Chapter A.) An urbanized area also may be divided into central city or cities and urban fringe as defined below.

Central cities.-Although an urbanized area may contain more than one city of 50,000 or more, not all cities of this size are necessarily central cities. The largest city of an area is always a central city. In addition, the second and third most populous cities in the area may qualify as central cities provided they have a population of at least one-third of that of the largest city in the area and a minimum of 25,000 inhabitants. The names of the individual urbanized areas indicate the central cities of the areas. The sole exception to this rule is found in the New York-Northeastern New Jersey Urbanized Area, the central cities of which are New York City, Jersey City, and Newark.

Urban fringe.-The urban fringe includes that part of the urbanized area which is outside the central city or cities. The following types of areas are embraced if they are contiguous to the central city or cities or if they are contiguous to any area already included in the urban fringe:

1. Incorporated places with 2,500 inhabitants or more in 1940 or at a subsequent special census conducted prior to 1950.

2. Incorporated places with fewer than 2,500 inhabitants containing an area with a concentration of 100 dwelling units or more with a density in this concentration of 500 units or more per square mile. This density represents approximately 2,000 persons per square mile and normally is the minimum found associated with a closely spaced street pattern.

3. Unincorporated territory with at least 500 dwelling units per square mile.

4. Territory devoted to commercial, industrial, transportational, recreational, and other purposes functionally related to the central city.

Also included are outlying noncontiguous areas with the required dwelling unit density located within 11⁄2 miles of the main contiguous urbanized part, measured along the shortest connecting highway, and other outlying areas within one-half mile of such noncontiguous areas which meet the minimum residential density

rule.

TYPES OF PLACES

The term "place" refers to a concentration of population regardless of legally prescribed limits, powers, or functions. Thus, some areas having the legal powers and functions characteristic of incorporated places are not recognized as places.

Incorporated places.-In a majority of instances, however, the legally prescribed limits of incorporated places serve to define concentrations of population. Of the 18,548 places recognized in the 1950 Census, 17,118 are incorporated as cities, towns, villages, or boroughs. In New England, New York, and Wisconsin, however, towns, although they may be incorporated, are minor civil divisions of counties and are not considered as places. Similarly, in the States in which townships possess powers and functions identical with those of villages, the township is not classified as a place. Although areas of this type are not recognized

as places, their densely settled portions may be recognized as unincorporated places or as a part of an urban fringe.

Unincorporated places. In addition to incorporated places, the 1950 Census recognizes 1,430 unincorporated places. These unincorporated places, which contain heavy concentrations of population, are recognized as places by virtue of their physical resemblance to incorporated places of similar size. To make this recognition possible, the Bureau of the Census has defined boundaries for all unincorporated places of 1,000 inhabitants or more which lie outside the urban fringes of cities of 50,000 inhabitants or more. Because local practice as to incorporation varies considerably from one part of the country to another, some States have very few if any such unincorporated places and others have a great many. Although there are also unincorporated places within the urban fringe, it was not feasible to establish boundaries for such places, and, therefore, they are not separately identified. Urban places. In the 1950 Census urban places comprise incorporated and unincorporated places of 2,500 inhabitants or more. Because incorporated places of fewer than 2,500 which lie in the urban fringe are not recognized as urban places and because unincorporated places of 2,500 or more are not identified in the urban fringe, the total population of urban places is somewhat less than the total urban population.

FARM POPULATION-RURAL AND URBAN

The farm population for 1950, as for 1940 and 1930, includes all persons living on farms without regard to occupation. In determining farm and nonfarm residence in the 1950 Census, however, certain special groups were classified otherwise than in earlier censuses. In 1950, persons living on what might have been considered farm land were classified as nonfarm if they paid cash rent for their homes and yards only. A few persons in institutions, summer camps, "motels," and tourist camps were classified as farm residents in 1940, whereas in 1950 all such persons were classified as nonfarm. For the United States as a whole, there is evidence from the Current Population Survey that the farm population in 1950 would have been about 9 percent larger had the 1940 procedure been used.

In most tables, data by farm residence are presented for the rural-farm population only, since virtually all of the farm population is located in rural areas. Only 1.2 percent of the farm population lived in urban areas in 1950. Figures on the urbanfarm population are shown in tables 13, 34, 42, and 50.

RURAL-NONFARM POPULATION

The rural-nonfarm population includes all persons living outside urban areas who do not live on farms. In 1940 and earlier, persons living in the suburbs of cities constituted a large proportion of the rural-nonfarm population. The effect of the new urban-rural definition has been to change the classification of a considerable number of such persons to urban. The ruralnonfarm population is, therefore, somewhat more homogeneous than under the old definition. It still comprises, however, persons living in a variety of types of residences, such as isolated nonfarm homes in the open country, villages and hamlets of fewer than 2,500 inhabitants, and some of the fringe areas surrounding the smaller incorporated places.

STANDARD METROPOLITAN AREAS

Origin and Purpose

It has long been recognized that, for many types of social and economic analysis, it is necessary to consider as a unit the entire population in and around the city whose activities form an integrated social and economic system. Prior to the 1950 Census, areas of this type had been defined in somewhat different ways by various agencies. Leading examples were the metropolitan districts of the Census of Population, the industrial areas of the Census of Manufactures, and the labor market areas of the Bureau

of Employment Security. The usefulness of data published for any of these areas was limited by this lack of comparability.

Accordingly, the Bureau of the Census in cooperation with a number of other Federal agencies, under the leadership of the Bureau of the Budget, established the "standard metropolitan area" so that a wide variety of statistical data might be presented on a uniform basis. Since counties instead of minor civil divisions are used as the basic component of standard metropolitan areas except in the New England States, it was felt that many more kinds of statistics could be compiled for them than for metropolitan districts. These new areas supersede not only the metropolitan districts but also the industrial areas and certain other similar areas used by other Federal agencies.

Definitions

Except in New England, a standard metropolitan area is a county or group of contiguous counties which contains at least one city of 50,000 inhabitants or more. In addition to the county, or counties, containing such a city, or cities, contiguous counties are included in a standard metropolitan area if according to certain criteria they are essentially metropolitan in character and socially and economically integrated with the central city. For a description of the standard metropolitan areas in this State, if any, see p. xxx.

Criteria of metropolitan character.-These criteria relate primarily to the character of the county as a place of work or as a home for concentrations of nonagricultural workers and their dependents. Specifically, these criteria are:

1. The county must (a) contain 10,000 nonagricultural workers, or (b) contain 10 percent of the nonagricultural workers working in the standard metropolitan area, or (c) have at least one-half of its population residing in minor civil divisions with a population density of 150 or more per square mile and contiguous to the central city.

2. Nonagricultural workers must constitute at least twothirds of the total number of employed persons of the county.

Criteria of integration.-The criteria of integration relate primarily to the extent of economic and social communication between the outlying counties and the central county as indicated by such items as the following:

1. Fifteen percent or more of the workers residing in the contiguous county work in the county containing the largest city in the standard metropolitan area, or

2. Twenty-five percent or more of the persons working in the contiguous county reside in the county containing the largest city in the standard metropolitan area, or

3. The number of telephone calls per month to the county containing the largest city of the standard metropolitan area from the contiguous county is four or more times the number of subscribers in the contiguous county.

Areas in New England.—In New England, the city and town are administratively more important than the county, and data are compiled locally for such minor civil divisions. Here towns and cities were the units used in defining standard metropolitan areas, and some of the criteria set forth above could not be applied. In their place, a population density criterion of 150 or more persons per square mile, or 100 or more persons per square mile where strong integration was evident, has been used.

Central cities.—Although there may be several cities of 50,000 or more in a standard metropolitan area, not all are necessarily central cities. The largest city in a standard metropolitan area is the principal central city. Any other city of 25,000 or more within a standard metropolitan area having a population amounting to one-third or more of the population of the principal city is also a central city. However, no more than three cities have been defined as central cities of any standard metropolitan area. The name of every central city is included in the name of the area, with the exception that in the case of the New York-Northeastern New Jersey Standard Metropolitan Area, "Jersey City" and "Newark”

are not part of the name. Data for standard metropolitan areas located in two or more States are presented in the report for the State containing the principal central city.

Difference Between Standard Metropolitan Areas and
Metropolitan Districts

Since the metropolitan district was built up from minor civil divisions and since the standard metropolitan area is usually composed of whole counties, the standard metropolitan area ordinarily includes a larger territory than the corresponding metropolitan district. There are, however, cases in which parts of the metropolitan district, as defined in 1940, do not fall within any standard metropolitan area. It is also true that in a number of cases single metropolitan districts of 1940 have been split into two standard metropolitan areas. Many metropolitan districts would have been changed, of course, had they been brought up to date for 1950.

In general then, the two kinds of areas are not comparable. Since metropolitan districts were defined almost wholly in terms of density and standard metropolitan areas include whole counties selected on the basis of more complicated criteria, the population density of the standard metropolitan areas is considerably lower on the average and shows more variation from one area to another. Differences between the two types of areas are relatively small in New England, and would have been even less had the metropolitan districts been brought up to date.

Difference Between Standard Metropolitan Areas
and Urbanized Areas

The standard metropolitan area can be characterized as the metropolitan community as distinguished from both the legal city and the physical city. Standard metropolitan areas are larger than urbanized areas and in most cases contain an entire urbanized area. However, in a few instances, the fact that the boundaries of standard metropolitan areas are determined by county lines, and those of urbanized areas by the pattern of urban growth, means that there are small segments of urbanized areas which lie outside standard metropolitan areas. In general then, urbanized areas represent the thickly settled urban core of the standard metropolitan areas, with the exceptions noted above. Because of discontinuities in land settlement, there are also some cases in which a single standard metropolitan area contains two urbanized areas. The lists of urbanized areas and of standard metropolitan areas also differ somewhat because the former had to be established for cities of 50,000 or more before 1950, whereas the latter were established for cities of 50,000 or more as determined in the 1950 Census.

QUALITY OF data for sMALL AREAS

Data for the smaller areas represent the work of only a few enumerators (often only one or two). The misinterpretation by an enumerator of the instructions for a particular item may, therefore, have an appreciable effect on the statistics for a very small community-e. g., places of less than 10,000 inhabitants and particularly places of less than 2,500 inhabitants-even though it would have a negligible effect upon the figures for a large area.

MEDIANS

Medians are presented in connection with the data on age, years of school completed, and income which appear in this volume. 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. In the computation of medians, cases for which the information was not reported are omitted. The median income for families and unrelated individuals is based on the total number reporting, including those reporting no income. The median income for persons is based on the distribution of those reporting $1 or more.

RACE AND COLOR

Definitions

The concept of race as it has been used by the Bureau of the Census is derived from that which is commonly accepted by the general public as reflected in the action of legislative and judicial bodies of the country. It does not, therefore, reflect clear-cut definitions of biological stock, and several categories obviously refer to nationalities. Although it lacks scientific precision, it is doubtful whether efforts toward a more scientifically acceptable definition would be appreciably productive, given the conditions under which census enumerations are carried out. The information on race is ordinarily not based on a reply to questions asked by the enumerator but rather is obtained by observation. Enumerators were instructed to ask a question when they were in doubt. Experience has shown that reasonably adequate identification of the smaller "racial" groups is made in areas where they are relatively numerous but that representatives of such groups may be misclassified in areas where they are rare.

Color.

The term "color" refers to the division of population into two groups, white and nonwhite. The group designated as "nonwhite" consists of Negroes, Indians, Japanese, Chinese, and other nonwhite races. Persons of Mexican birth or ancestry who were not definitely Indian or of other nonwhite race were classified as white in 1950 and 1940. In the 1930 publications, Mexicans were included in the group "Other races," but the 1930 data published in this report have been revised to include Mexicans in the white population.

Negro. In addition to full-blooded Negroes, this classification also includes persons of mixed white and Negro parentage and persons of mixed Indian and Negro parentage unless the Indian blood very definitely predominates or unless the individual is accepted in the community as an Indian.

American Indian. In addition to full-blooded Indians, persons of mixed white and Indian blood are included in this category if they are enrolled on an Indian reservation or agency roll. Also included are persons of mixed Indian blood if the proportion of Indian blood is one-fourth or more, or if they are regarded as Indians within the community. Indians living in Indian Territory or on reservations were not included in the population until 1890. Other races. Separate statistics are given in this volume for Japanese and Chinese. The category "All other" includes Filipinos, Koreans, Asiatic Indians, etc.

Mixed Parentage

Persons of mixed parentage are classified according to the race of the nonwhite parent and mixtures of nonwhite races are generally classified according to the race of the father.

In 1950, for the first time, an attempt was made to identify persons of mixed white, Negro, and Indian ancestry living in certain communities in the eastern United States in a special category so they might be included in the categories "Other races" and "All other" rather than being classified white, Negro, or Indian. This identification was accomplished with varying degrees of success, however. These groups are not shown separately, but they are included in the "nonwhite" total. The communities in question are of long standing and are locally recognized by special names, such as "Siouian" or "Croatan," "Moor," and "Tunica." In previous censuses, there had been considerable variation in the classification of such persons by race.

AGE Definitions

The age classification is based on the age of the person at his last birthday as of the date of enumeration, that is, the age of the person in completed years. The enumerator was instructed to obtain the age of each person as of the date of his visit rather than as of April 1, 1950.

Assignment of Unknown Ages

When the age of a person was not reported, it was estimated on the basis of other available information such as marital status, school attendance, employment status, age of other members of the family, and type of household. Age was estimated by this procedure in the 1950 Census for 0.19 percent of the population of the United States. This method of assigning unknown ages on the basis of related information was used for the first time in the 1940 Census when estimates of age were made for 0.16 percent of the population of the United States. In previous censuses, with the exception of 1880, persons of unknown age were shown in a separate category. The summary totals for "14 years and over" and "21 years and over" for earlier censuses presented in this volume include all persons of "unknown age" since there is evidence that most of the persons for whom age was not reported were in the age classes above these limits.

Errors in Age Statistics

A considerable body of evidence exists which indicates that age is misreported in several characteristic ways and that certain age groups are less completely enumerated than others in censuses. A comparison of age distributions from the 1950 Census with age distributions based on figures from the 1940 Census and brought up-to-date from official records of births, deaths, and migration, suggests that this generalization is also true for the 1950 Census. This comparison shows that, for the United States as a whole, there appears to be an underenumeration of children under 5 of approximately 4.8 percent as compared with about 7.6 percent in 1940. Males between the ages of 18 and 24 also appear to have been relatively underenumerated. Likewise, there appears to be a deficit of persons in the age range 55 to 64 years, which, however, is more than offset by an excess over the number expected in the age group 65 years old and over.

In addition to errors in the statistics for broad-age groups arising from underenumeration and the misstatement of age, there is a tendency to report age in multiples of 5. This tendency is apparent in statistics for single years of age in which the frequencies for single years ending in 0 and 5 are frequently greater than those for the two adjoining years. This type of misreporting presumably occurs in situations in which the respondent, in the absence of specific knowledge as to his exact age or the age of the person for whom he is reporting, gives an approximate figure. The returns also exaggerate the number of centenarians, particularly among nonwhite persons. In general, the degree of inaccuracy in reported ages is greater for adults than for children.

NATIVITY

In this volume, the population is classified according to place of birth into two basic groups, native and foreign born. A person born in the United States or any of its Territories or possessions is counted as native. Also included as native is the small group of persons who, although born in a foreign country or at sea, were American citizens by birth because their parents were American citizens. Since the Republic of the Philippines was established as an independent country in 1946, persons living in the United States who had been born in the Philippine Islands were classified as foreign born in the 1950 Census whereas in earlier censuses they had been classified as native. The small number of persons for whom place of birth was not reported were assumed to be native.

Because of the declining numerical importance of the foreignborn population, nativity has not been used so extensively for cross-classifications in 1950 as in earlier censuses. Information on the nativity and parentage of the white population and country of origin of the foreign white stock will be published in a special report. The distribution of the separate nonwhite races by nativity and more detailed data on the foreign-born nonwhite population will be presented in a later publication.

CITIZENSHIP

The classification of the population by citizenship embraces two major categories, citizen and alien. Citizens are subdivided into native and naturalized. It is assumed that all natives are citizens of the United States. In addition to the citizen and alien categories, there is a third group, made up of foreign-born persons for whom no report on citizenship was obtained, designated "citizenship not reported." Since it is likely that most of these persons are aliens, they are often included with "alien" in summary figures for total aliens.

MARITAL STATUS AND MARRIED COUPLES

Definitions

Marital status. In the 1950 Census, data on marital status are based on replies to the question “Is he now married, widowed, divorced, separated, or [has he] never [been] married?" The classification refers to the status at the time of enumeration. Persons classified as "married" comprise, therefore, both those who have been married only once and those who remarried after having been widowed or divorced. Persons reported as separated or in common-law marriages are classified as married. Those reported as never married or with annulled marriages are classified as single. Since it is probable that some divorced persons are reported as single, married, or widowed, the census returns doubtless understate somewhat the actual number of divorced persons who have not remarried.

In some tables, the category "Married" is further divided into "Married, spouse present" and "Married, spouse absent." In the office processing, this classification was made for a 20-percent sample of the data collected. A person is classified as "married, spouse present" if the person's husband or wife was reported as a member of the household or quasi household in which the person was enumerated, even though he or she may have been temporarily absent on business or vacation, visiting, in a hospital, etc., at the time of the enumeration. The number of married men with wife present who are classified as heads of households is the same as the number of wives of heads of households shown in the tables on relationship to head of household, except for differences arising from sampling variation or from methods used in processing the data. The number shown as not head of household is the same as the number of married couples without own household, except for differences arising from processing methods used.

Persons reported as separated are included in the group designated as "Married, spouse absent." Separated persons include those with legal separations, those living apart with intentions of obtaining a divorce, and other married persons permanently or temporarily estranged from their spouse because of marital discord. The group "Other married, spouse absent" includes married persons employed and living for several months at a considerable distance from their homes, those whose spouse was absent in the armed forces, in-migrants whose spouse remained in another area, husbands or wives of inmates of institutions, and all other married persons (except those reported as separated) whose place of residence was not the same as that of their spouse. Differences between the number of married men and the number of married women arise from spouses having their usual residences in different areas, from differences in the completeness of enumeration of married men and women, and from response and processing errors.

Married couple.-A married couple is defined as a husband and his wife enumerated as members of the same household or quasi household. As indicated above, this classification was made for a 20-percent sample of the data collected. Married couples are classified as "with own household" if the husband is head of the household. Other married couples, classified as "without own household," may be living in households as relatives of the head

or as lodgers or employees, or they may be living in quasi households, such as large rooming houses or hotels.

Comparability

The category "Separated" was included in the question on marital status for the first time in 1950. Previously, the question included the categories single, married, widowed, and divorced. This change may have made the number of persons reported as divorced somewhat smaller in 1950 than it would have been under the earlier procedure.

In 1950, as in previous censuses, marital status was not reported for a small number of persons. For such persons marital status was estimated in 1950 and 1940 on the basis of age and the presence of spouse or children. Because of the methods used in 1950, however, some persons who would have been classified as single under the 1940 procedure were classified as "married, spouse absent" or "widowed" in 1950.

To obtain the marital status distribution of the population 14 years old and over for 1890 to 1930 it has been necessary to assume that the small number of persons under 15 years old classified as married, widowed, divorced, or with marital status not reported were 14 years old.

HOUSEHOLD AND FAMILY Definitions

Household. A household includes all the persons who occupy a house, an apartment or other group of rooms, or a room, that constitutes a dwelling unit. In general, a group of rooms occupied as separate living quarters is a dwelling unit if it has separate cooking equipment or a separate entrance; a single room occupied as separate living quarters is a dwelling unit if it has separate cooking equipment or if it constitutes the only living quarters in the structure. A household includes the related family members and also the unrelated persons, if any, such as lodgers, foster children, wards, or employees who share the dwelling unit. A person living alone in a dwelling unit or a group of unrelated persons sharing the same dwelling unit as partners is also counted as a household. The count of households excludes groups of persons living as members of a quasi household (see below).

The average population per household is obtained by dividing the population in households by the number of households. It excludes persons living in quasi households.

Quasi household.-A quasi household is a group of persons living in quarters not classified as a dwelling unit, for example, in a house with at least five lodgers, or in a hotel, institution, labor camp, or military barracks.

Family. A family, as defined in the 1950 Census, is a group of two or more persons related by blood, marriage, or adoption and living together; all such persons are regarded as members of one family. The number of families was determined from the number of persons classified as heads of families; this classification was made for a 20-percent sample of the data collected. A family may comprise persons in either a household or a quasi household. If the son of the head of the household and the son's wife are members of the household they are treated as part of the head's family. A lodger and his wife who are not related to the head of the household, or a resident employee and his wife living in, are considered as a separate family, however. Thus, a household may contain more than one family. A household head living alone or with nonrelatives only is not regarded as a family. Some households, therefore, do not contain a family.

The average population per family is obtained by dividing the population in families by the number of families. In Chapter B, the population in families includes, in addition to family members, the small number (about 145,000) of unrelated individuals under 14 years old who had not been tabulated separately at the time this report was prepared.

Unrelated individual.-Unrelated individuals are those persons (other than inmates of institutions) who are not living with any relatives. In the office processing, this classification was made for a 20-percent sample of the data collected. An unrelated individual may be (a) a household head living alone or with nonrelatives only, (b) a lodger or resident employee with no relatives in the household, or (c) a member of a quasi household who has no relatives living with him. Thus, a widow who occupies her house alone or with one or more persons not related to her, a roomer not related to anyone else in the dwelling unit, a maid living as a member of her employer's household but with no relatives in the household, and a resident staff member in a hospital living apart from any relatives are all examples of unrelated individuals.

Institutional population. The institutional population includes those persons living as inmates in such places as homes for delinquent or dependent children, homes and schools for the mentally or physically handicapped, places providing specialized medical care, homes for the aged, prisons, and jails. Staff members and their families are not included in the institutional population. Inmates of institutions are not counted as "unrelated individuals,” largely because statistics on "unrelated individuals" are more useful to consumers of data on labor force, income, and housing statistics if they exclude such inmates.

The number of inmates of institutions is shown in the tables in Chapter B. Inmates 14 years old and over are shown in certain employment status tables in Chapters B and C and in table 90 on income in Chapter C.

Family status.-In table 90, persons 14 years old and over are classified into the categories family head, wife, or other relative of family head, unrelated individual, and inmate of institution. This classification differs from that in tables 58 and 59 which pertains to relationship to household head (see below).

Comparability

Earlier census data.-Minor changes in the instructions for identifying dwelling units in 1950 as compared with 1940 may have affected to a slight extent the increase in households between the two dates. For example, in the 1940 Census, the occupants of a lodginghouse were regarded as constituting a quasi household if the place included 11 or more lodgers; in the 1950 Census the criterion was reduced to 5 or more lodgers. As a result of this change, the number of quasi households probably doubled in many areas. In general, however, the number of households and the number of occupied dwelling units in the 1950 Census may be regarded as comparable with the number of "families," "private households," and occupied dwelling units as shown in the census reports for 1930 and 1940.

In the 1950 Census, the number of households and the number of occupied dwelling units were identical by definition; small differences between these numbers appear in the published reports, however, because the data for the Population and the Housing reports were processed independently.

The term "family" as used in the 1950 Census is not comparable with that used by the Bureau of the Census before 1947. The new definition excludes the large number of household heads with no relatives in the household who would have been classified as families under the old definition. On the other hand, the new definition includes the small number of groups of mutually related lodgers or employees in households and of mutually related persons in quasi households who would not have been classified as families under the old definition. The net effect has been to reduce the number of families.

In certain Population and Housing reports of the 1940 Census, the average population per household included the relatively small number of persons living in quasi households. Such persons were excluded in calculating the average population per household shown in the present volume.

The coverage of the institutional population in the 1950 Census is somewhat more inclusive than that in the 1940 Census. For example, patients in tuberculosis sanataria were included in 1950 but not in 1940. Furthermore, the identification of certain other types of institutions, such as nursing, convalescent, and rest homes, was probably improved in 1950 by the use of lists of such places compiled from welfare agencies.

Current Population Survey.-Estimates of the number of households and of the number of families for the United States as a whole are published annually from the Current Population Survey. The estimates based on this survey for March 1950 were higher than the figures obtained from the census in April 1950. These differences may be attributed to such factors as sampling variability, methods used in weighting the sample figures, and differences between the interviewers with respect to training and experience.

RELATIONSHIP TO HEAD OF HOUSEHOLD Definitions

Head of household.-One person in each household is designated as the "head." The number of heads, therefore, is equal to the number of households. The head is usually the person regarded as the head by the members of the household. Married women are not classified as heads if their husbands are living with them at the time of the census.

Wife. The total number of females shown under the heading "wife" is ordinarily somewhat less than the total number of married women with husband present, since the category "Wife" in the relationship tables includes only wives of heads of households. As indicated in the section on "Marital status," the number of "wives" is directly comparable with data in the marital status tables on the number of married men with wife present who are heads of households. Either of these figures may be used to indicate the number of "husband-wife households."

Child. This category includes sons and daughters, stepchildren, and adopted children of the head regardless of their age or marital status. It excludes sons-in-law and daughters-in-law and, of course, any children of the head no longer living in the household.

Grandchild. This category comprises all persons living in the household who are sons, daughters, stepchildren, or adopted children of a child of the head.

Parent. This class comprises both parents and parents-in-law of the head if living in the household.

Other relative. This group includes such relatives of the head as sons-in-law, sisters-in-law, nephews, brothers, aunts, grandparents, cousins, and great-grandchildren, if these are members of the household.

Lodger. All persons in households who are not related to the head, except resident employees and their families, are counted as lodgers. Among these persons are lodgers, roomers, and boarders, and their relatives residing in the same household. Also included are partners, foster children, and wards.

Resident employee. This category consists of all employees of the head of the household who usually reside in the household with their employer (mainly cooks, maids, nurses, and hired farm hands), and their relatives residing in the same household. In 1940, relatives of resident employees living in the same household were shown as lodgers.

Head of quasi household.-Heads of quasi households are usually managers or officers in institutions, hotels, lodginghouses, and similar establishments. If the landlady in a rooming house reported herself as the head but her husband was a member of the quasi household, he was designated as head for consistency with the treatment of married heads and wives of heads of households. The number of heads of quasi households also represents the number of quasi households.