American Community Survey (ACS)

The American Community Survey (ACS) is an ongoing national survey conducted by the U.S. Census Bureau. Part of the federal decennial census program, the ACS was designed to replace the long form or sample portion of the decennial census, starting in 2010. By conducting monthly surveys of a sample of the U.S. population, the ACS collects economic, social, and housing information continuously rather than every 10 years. The ACS does not replace the decennial enumeration, which is constitutionally mandated for apportioning congressional seats. It is expected that the ACS program will improve the quality of the decennial census, because the elimination of long-form questions should increase response and allow more focused non-response follow-up.

Eventually, the ACS will supply data for the same geographic levels that have traditionally been available from the census long form, including sub-county areas such as census tracts and block groups. The ACS sample sizes are not large enough to support annual releases for all geographic areas. For smaller areas, the ACS data are averaged over multiple years. Annual data are available for populations of 65,000 or more. Annual estimates from the 2005 ACS were released in 2006. Three-year averages will be released for areas with 20,000 or more people, and 5-year averages will be available for the remaining areas. Three-year averaged data will be available starting in 2008, and the 5-year averaged data will first be available in 2010. After 2010, data for all geographic data will be updated annually, using the rolling 3- or 5-year averages for the smaller areas.

The Census Bureau has conducted ACS tests in select counties since the mid-1990s. In 2005, the housing unit sample was expanded to its full size, which includes all U.S. counties and equivalents, the District of Columbia, and Puerto Rico. The ACS was expanded to include group quarters facilities in 2006. As an ongoing program, funding for the American Community Survey must be approved by Congress annually as part of the federal budget process. Current ACS implementation plans could change in the future if funding is not approved.