The American Community Survey: Development, Implementation, and Issues for Congress

Jennifer D. Williams
Specialist in American National Government

The American Community Survey (ACS) is the U.S. Census Bureau’s replacement for the decennial census long form, which, since 1940, had gathered detailed socioeconomic and housing data from a representative population sample in conjunction with the once-a-decade count of all U.S. residents. Unlike the long form, with its approximately 17% sample of U.S. housing units in 2000, the ACS is a “rolling sample” or “continuous measurement” survey of about 250,000 housing units a month (totaling about three million a year). The data are aggregated to produce one-year, three-year, and five-year estimates that are much more timely than the long-form estimates were. As were the long-form data, ACS data are used in program formulas that determine the annual allocation of certain federal funds, currently more than $400 billion, to states and localities.

The ACS has several other features in common with the long form: the topics covered are largely the same; survey questionnaires are mailed to housing units, filled out, and returned by mail; responses are mandatory; and the Bureau follows up, by telephone or in-person visits, with households that do not return completed questionnaires. The ACS is conducted under the authority of Title 13, Sections 141 and 193, of the United States Code; so was the long form. Title 44, Section 3501, of the Code, the Paperwork Reduction Act of 1995, and its implementing regulations require federal agencies to obtain Office of Management and Budget approval before collecting information from the public. On the long form, the Bureau could gather only data that were mandatory for particular programs, required by federal law or regulations, or needed for the Bureau’s operations. Likewise, the ACS can collect only necessary information.

The limited ACS sample size makes longer cumulations of data necessary to generate reliable estimates for less populous areas. Yearly averages have been available since 2006, but only for geographic areas with 65,000 or more people. The first three-year period estimates, based on data collected in 2005, 2006, and 2007, became available in 2008 for areas with at least 20,000 people. The first five-year averages, of data gathered from 2005 through 2009, were released on December 14, 2010, for areas from the most populous to those with fewer than 20,000 people. A concern noted by some data users is that the present ACS sample size results in less-detailed fiveyear data products for smaller geographic areas—census tracts and block groups—than were available every 10 years from the long form. A related issue is data quality, especially for small areas.

An ongoing concern for some Members of Congress and their constituents is that responses to the ACS are required. The conferees on H.J.Res. 2, the Consolidated Appropriations Resolution, 2003 (P.L. 108-7; 117 Stat. 11), included $1 million for the Bureau to test a voluntary versus mandatory ACS. The test findings, reported in 2003 and 2004, showed a 20.7-percentage-point drop in the overall ACS response rate when answers were optional. The Bureau estimated that if the survey became voluntary, maintaining data reliability would necessitate increasing the annual sample size from about three million to 3.7 million housing units, at an additional cost of at least $59.2 million per year in FY2005 dollars. Two bills from the 111th Congress, H.R. 3131 and H.R. 5046, proposed making almost all ACS responses optional. H.R. 931 has been introduced in the 112th Congress for the same purpose.


Date of Report: May 12, 2011
Number of Pages: 24
Order Number: R41532
Price: $29.95

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