Income was ascertained for all persons 14 years of age and over (1970) (15 years and over in 1980 and 1990). Income refers to total income for the individual types of income listed in the census and excludes some types of income, e.g. income from the sale of property, unless the respondent’s business was selling such property, and refers to income for the previous year. Thus, income in the 1970 census is for 1969, income in the 1980 census is for 1979 and income in the 1990 census is for 1989.
Income is tabulated by several intervals which vary from census to census as income distribution change. Per capita income is also tabulated.
Family Income is the total income of all members of the family aged 14/15 years and older living with the family at the time of the census. Thus income from persons who may have been members of the family in the previous year, but were not living with the family at the time of the census, is not counted toward family income.
Poverty is calculated for families and unrelated individuals (excluding college students in dormitories and Armed Forces personnel in barracks). The poverty level is based on an “economy” food plan designed by the Department of Agriculture for “emergency or temporary use when funds are low.” This index was established in 1969 and is based on the amount of funds required by families of different size. The cutoffs are changed each year based on the consumer price index. Other changes in the poverty index has taken place from time to time.
From 1970 to 1980 changes in the poverty definition included these modifications:
Farm families and farm unrelated individuals no longer had a set of poverty thresholds different from nonfarm.
The thresholds by size of family were extended from seven or more persons to nine or more.
Separate thresholds for families with a female householder with no husband present and all other families were eliminated.
Persons for Whom Poverty Status is Determined.
Poverty rates are calculated using only persons for whom poverty status is determined, i.e. all persons except instituionalized persons, persons in military group quarters and in college dormitories, and unrelated individuals under 15 years old.
Income data should always be used with caution because of reporting errors, and non-reporting or under-reporting.The Census Bureau uses extensive checking, editing, and imputing of income values. Income data from the Census are not comparable with records of other federal agencies (IRS, Social Security, BEA). Differences should be expected.