As part of the Bureau's continuing effort to improve the quality and usefulness of its income and poverty data, several important modifications were made in the collection and presentation of data from the March Current Population Survey (CPS). All 1979 poverty figures mentioned in the text are based on the full set of modifications made in the March 1980 CPS. However, references to changes between 1978 and 1979 are based on statistics derived using comparable procedures for both years. A detailed discussion of the modifications can be found in the section entitled "Modifications to the March 1980 CPS."

It should also be noted that the poverty estimates in this report differ slightly from those published in the 1979 advance report (Series P-60, No. 125) as a result of a correction to the weighting procedure. The most noticeable differences appear in estimates for the Spanish-origin population. A discussion of this correction can be found in the section, "Revisions to Previously Published March 1980 Estimates."

This report presents detailed social and economic statistics for the population of the United States below the poverty level in 1979 based on the March 1980 Current Population Survey (CPS). As in previous poverty reports, data are presented by selected characteristics, such as race, family relationship, type of residence, education, work experience, and source of income. It should be noted that the term "householder" is now used in both the text and detailed tables of this report in place of the term "head" which appeared in earlier reports. See "Implementation of the Householder Concept" in the section, "Modifications to the March 1980 CPS" for further details.

The poverty threshold for a nonfarm family of four persons was $7,412 in 1979, about 11.3 percent higher than the comparable 1978 threshold of $6,662. Poverty thresholds are updated every year to reflect changes in the average annual Consumer Price Index (CPI). (See appendix A for a detailed explanation of the poverty definition.) In this text, the terms "poverty," "low-income," and "poor" are used interchangeably. Also, the phrases "families with a male householder" and "families with a female householder" have the same meaning as "families maintained by men" and "families maintained by women."