The data presented in this section of the Abstract relate to the population of continental United States, except for Table 1, which gives the population of the United States and all its outlying territories and possessions. Figures are given for States and counties, for cities and other urban places having 2,500 inhabitants or more, and for urban, rural-farm, and rural-nonfarm areas.
Urban and rural areas.— Urban population, as defined by the Census Bureau, is in general that residing in cities and other incorporated places having 2,500 inhabitants or more, the remainder being classified as rural. In New Hampshire, Massachusetts, and Rhode Island, town (townships) are classified as urban if they have more than 2,500 inhabitants and certain urban characteristics, and a few large townships in other States are likewise classified as urban under a special rule; these townships and the New England towns constituting the exceptions to the general definition of urban population are indicated by asterisks in Tables 16 to 19.
Farm population.— Both rural and urban population are subdivided into farm and nonfarm, though for the urban-farm population nothing except the total number is given. The farm population comprises all persons living on farms, without regard to occupation. The rural-farm population includes more than 99 per cent of the total farm population. The rural-nonfarm (or "village") population includes small manufacturing villages and trading centers, unincorporated suburban areas, mining settlements, etc., and a considerable number of families living in the open country but not on farms.
Color and nativity.— In the main tabulations of the population by color or race, three groups are distinguished, namely, white, Negro, and "Other races." In a few of the tables, however, the third group is subdivided into its constituent parts, the principal ones being Mexican, Indian, Chinese, and Japanese. Mexicans were shown separately for the first time in 1930, the enumerators being instructed to return as Mexican all persons born in Mexico or having parents born in Mexico who were not definitely white, Negro, Indian, Chinese, or Japanese. The Mexican population was for the most part included in the white population in 1920 and in earlier censuses. For comparative purposes, however, the Mexican population in 1920 and 1910 has been estimated, and the 1920 and 1910 figures for the white population in most of the tables have been adjusted to a basis comparable with those for 1930 by subtracting these estimates.
In the classification by nativity, a person born in the United States or in any of its territories or possessions in counted as native. The tabulations showing nativity and parentage are for the most part restricted to the white population. The native white population is usually divided into two groups, those of native parentage (both parents native) and those of foreign or mixed parentage (one or both parents foreign born). The second group is in some tables subdivided so as to show separately those of foreign parentage (both parents foreign born) and those of mixed parentage (one parent native and the other foreign born).
State of birth.— The native population is classified by State of birth, the resulting figures giving some indication of interstate migration.
Country of birth.— The foreign-born population is classified according to country of birth, the European countries being presented in accordance with their postwar boundaries.