American Community Survey
http://www.census.gov/acs/www and related web pages. Accessed August 24, 2010.
The American Community Survey (ACS) is an annual nationwide survey designed to supplement the decennial census. The survey, based on the decennial census long form, produces population and housing information every year instead of every 10 years. Annual estimates of demographic, social, economic, and housing characteristics are available for geographic areas with a population of 65,000 or more. This includes the nation, all states, the District of Columbia, all congressional districts, approximately 800 counties, and 500 metropolitan and micropolitan statistical areas. Multi-year estimates are available for smaller geographic areas. During the demonstration stage (2000 to 2004), the U.S. Census Bureau carried out large-scale, nationwide surveys and produced reports for the nation, the states, and large geographic areas. The full implementation stage began in January 2005, with an annual housing unit (HU) sample of approximately 3 million addresses throughout the United States and 36,000 addresses in Puerto Rico. In 2006 approximately 20,000 group quarters were added to the ACS so that the datafully describe the characteristics of the population residing in geographic areas.Each year from 2005â€“2010, we selected approximately 2.9 million HU addresses in the U.S. and 36,000 HU addresses in Puerto Rico. Beginning in 2011, the following changes to the ACS sample designs were implemented:1)increased the housing unit sample in June 2011, bringing the size of the sample selected to 3.54 million addresses per year; 2)added several new housing unit sampling rates that better control the allocation of the sample and improve estimate reliability for small areas; 3)increased the follow-up sample to 100 percent in select geographic areas.