Specific concepts of the labor force, employment, and unemployment were developed in the later stages of the Depression of the 1930s. Before the 1930s, aside from attempts in some of the decennial censuses, no direct measurements were made of the number of jobless persons. Mass unemployment in the early 1930s increased the need for statistics, and widely conflicting estimates based on a variety of indirect techniques began to appear. Dissatisfied with these methods, many research groups, as well as State and municipal governments, began experimenting with direct surveys or samples of the population. In these surveys, an attempt was made to classify the population as employed, unemployed, or out of the labor force by means of a series of questions addressed to each individual. In most of the surveys, the employed were defined as persons with occupations ("gainful workers"), and the unemployed were defined as those who were not working but were "willing and able to work." These concepts did not meet the standards of objectivity that many technicians felt were necessary to measure either the level of unemployment at a point in time or changes over time. Counts of gainful workers did not have a current dimension, and the criterion "willing and able to work," when applied in specific situations, appeared to be too intangible and too dependent upon the interpretation and attitude of the persons being interviewed.
A set of precise concepts was developed in the late 1930s to address these various criticisms. The classification of an individual depended principally upon his or her actual activity within a designated period, that is, was the individual working, looking for work, or engaged in other activities? These concepts were adopted for the national sample survey of households, called the Monthly Report of Unemployment, initiated in 1940 by the Works Progress Administration.
The household survey was transferred to the Census Bureau in late 1942, and its name was changed to the Monthly Report on the Labor Force. The name was changed once more, in 1948, to the present Current Population Survey in order to reflect the survey's expanding role as a source for data on a wide variety of demographic, social, and economic characteristics of the population. In 1959, responsibility for analyzing and publishing the CPS labor force data was transferred to BLS; the Census Bureau continues to collect the data.
For a more information, please refer to Technical Paper 77, Design and Methodology. Chapter 1-1 Background and History of the CPS provides a more detailed history of the Current Population Survey. The Appendix to Unit 1 provides a detailed chronology of major events in CPS history.