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Handbook of Methods Current Population Survey History

Current Population Survey: History

Hover over the red dot to see historical information.

Timeline event 

  • 1940: The Work Projects Administration (WPA) launches the monthly Sample Survey of Unemployment, which will later become the Current Population Survey (CPS).
  • 1942: The U.S. Census Bureau assumes responsibility for the monthly unemployment survey, taking over from the Work Projects Administration.
  • 1945: The unemployment survey questionnaire is redesigned to improve the identification of people’s employment status, especially that of part-time and intermittent workers.
  • 1948: The monthly unemployment survey becomes widely known as the Current Population Survey (CPS).
  • 1953: High-speed electronic equipment is introduced for survey tabulations, greatly increasing the timeliness and scope of data available.
  • 1955: The survey reference week of the CPS is changed to the calendar week containing the 12th of the month, in order to align it with that of other key labor market surveys. Previously, the calendar week containing the 8th was used.
  • 1957: A seasonally adjusted national unemployment rate is introduced.
  • 1959: The CPS becomes a joint endeavor of the U.S. Census Bureau and the U.S. Bureau of Labor Statistics (BLS), with the Census Bureau continuing to collect and process the data and BLS assuming responsibility for the planning, analysis, and publication of labor force statistics.
  • 1966: The monthly national unemployment rate and other labor market data from the CPS are released simultaneously with payroll jobs data from the Current Employment Statistics Survey in The Employment Situation. Previously, the unemployment rate and selected labor force data were released about a week before the payroll statistics.
  • 1967: The concepts of employment and unemployment, as well as many related concepts, are refined following recommendations set forth in 1962 by the President’s Committee to Appraise Employment and Unemployment Statistics (“the Gordon Committee”).
  • 1979: The National Commission on Employment and Unemployment Statistics (“the Levitan Commission”) issues its final report, which would influence a number of later changes to the survey.
  • 1994: The survey questionnaire undergoes a major redesign to improve and expand labor market measures. Many of the refinements adopted are the result of recommendations from the Levitan Commission in 1979. The redesign also converts the questionnaire to a fully computer-based survey instrument.

Historical overview

Before the 1930s, there was no monthly survey to count the unemployed. In fact, at that time, there was no consensus among economists and statisticians about how the unemployed should be defined and how the unemployment rate should be calculated. Mass unemployment during the Great Depression increased the need for such statistics, and widely conflicting estimates based on a variety of 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 U.S. working-age population into one of three categories: employed, unemployed, or out of the labor force. Toward that end, a series of questions was asked about each individual.

By the late 1930s, a set of precise labor force concepts was developed to classify people as working, looking for work, or not in the labor force. These concepts were adopted for a national survey of households. Called the Monthly Report of Unemployment, the survey was initiated in 1940 by the Work Projects Administration. The survey was transferred to the U.S. Census Bureau in 1942 and was later renamed the Current Population Survey (CPS). The U.S. Bureau of Labor Statistics (BLS) assumed responsibility for the publication and analysis of the monthly CPS labor force data in 1959, while the Census Bureau continued to administer the survey. Since that time, the CPS has been a joint endeavor of the two statistical agencies.

Historical comparibility

Over the years, there have been continuous improvements to the survey. The definition of the unemployed, as well as the unemployment rate, however, have changed minimally since the concepts were first instituted.

Although the core labor force concepts have held up over time, data users should be aware that there are inevitable historical comparability issues and breaks with many CPS series, some more significant than others. 

Historical comparability issues with CPS data typically stem from one or more of the following:

  • Survey questionnaire changes

There have been relatively few changes to CPS questions over the years. The last major redesign, for example, occurred in 1994, when survey questions underwent substantial review and refinement to provide more precise and relevant data about a changing labor market. The survey also moved from a paper format to a computerized instrument at that time.

For information about changes to survey concepts and questions, see the historical comparability section of the CPS technical documentation.

  • Methodological or estimation procedure changes

Methodological and related changes do not occur often but are essential to ensuring that survey procedures conform to best practices and provide the highest quality data. The CPS has introduced a number of such improvements over its history, some of which had more impact on data comparability than others. Some of these changes are highly technical in nature, such as those related to sample design and to weighting estimates.

For information about the methodological and related changes, see the historical comparability section of the CPS technical documentation.

  • Population control adjustments

Population controls are independent estimates of population that are used to weight the CPS sample results in order to reflect the civilian noninstitutional population ages 16 and older. They are adjusted regularly, to reflect the latest information about population change. Since 2003, the population controls have been adjusted annually with the release of January data.  Prior to 2003, the population controls were adjusted less frequently. 

Some of the population control adjustments have caused significant shifts in estimates of the labor force and employment levels that have affected data comparability.

Information about the effects of population control adjustments on major data series is available in the CPS technical documentation.

  • Changes in the industry and occupational classification systems

BLS publishes employment and unemployment estimates pertaining to industries and occupations from the CPS. The Census Bureau uses standardized classification systems to assign a designated industry and occupation from survey responses, but these classification systems are revised periodically to reflect fundamental changes in industry structure and types of jobs over time. The revisions create changes in the way industries and occupations are grouped and defined—changes that often adversely affect the comparability of historical data. Some of the changes in classification represent complete breaks from previous data, affecting their comparability with more recent data.

Historical comparability of occupation and industry data from the Current Population Survey describes industry and occupational classification changes over time.


Last Modified Date: April 10, 2018