A household consists of all the persons who occupy a housing unit (see definition of housing unit in section below on Living quarters). The population per household is obtained by dividing the population in households by the number of households. The population per household is not shown for nonwhite persons in tracts where most of the nonwhite persons live in the homes of white persons as nonrelatives; these persons perform domestic service work, live as lodgers while attending college, or have some other special living arrangement.

All persons who are not members of households are classified as living in group quarters. Most of the persons in group quarters live in rooming houses, college dormitories, military barracks, or institutions. Inmates of institutions are persons for whom care or custody is provided in such places as homes for delinquent or dependent children; homes and schools for the mentally or physically handicapped; places providing specialized medical care for persons with mental disorders, tuberculosis, or other chronic disease; nursing and domiciliary homes for the aged and dependent; prisons; and jails.

For persons in households, five categories of relationship to head of household are recognized in this report:

1.The head of the household is the member reported as the head by the household respondent. However, if a married woman living with her husband is reported as the head, her husband is classified as the head for the purpose of census tabulations.
2.The wife of a head of a household is a woman married to and living with a household head. This category includes women in common-law marriages as well as women in formal marriages.
3.The children under 18 of the household head are the heads sons and daughters under 18 years old and also his stepchildren and adopted children of this age group.
4.Other relative of head, in this report, includes all persons who are related to the head of the household by blood, marriage, or adoption except those in the categories wife of head and children under 18 of head.
5. A nonrelative of the head is any member of the household who is not related to the household head by blood, marriage, or adoption. Lodgers, partners, resident employees, wards, and foster children are included in this category.

The three major race categories distinguished in this report are white, Negro, and other races. Among persons of other races are American Indians, Japanese, Chinese, Filipinos, Koreans, Asian Indians, and Malayans. Negroes and persons of other races taken together constitute nonwhite persons. Persons of Mexican birth or descent who are not definitely Indian or other nonwhite race are classified as white. In addition to persons of Negro and of mixed Negro and white descent, the category Negro includes persons of mixed Indian and Negro descent unless the Indian ancestry very definitely predominates or unless the person is regarded as an Indian in the community.