American Community Survey
The American Community Survey (ACS) is an annual survey taken by the U.S. Census Bureau. Data collected incudes social, economic, housing and population data. ACS provides data for the nation, states, counties and other geographic areas down to the block group level. Data profiles for selected detailed population groups such as Native Hawaiians and Filipinos are also available for higher level geographies such as the state and sometimes the City and County of Honolulu.
The ACS data are released in three waves each year. The first wave released is called the 1-year dataset and includes geographic areas with populations of 65,000 or more. The second wave is called the 3-year dataset (combining 3 years of survey data) and includes geographic areas with populations of 20,000 or more. The third wave is called the 5-year dataset (combining 5 years of survey data) and includes all geographic areas down to the block group level.
A good way to start your data search is to decide what geographic area you are interested in. Local level data is popular and for most areas below the county level, data users would need to use the 5-year ACS datasets. The next step is to obtain the data that you need. Geographic area profiles contain a wealth of information and will probably serve your needs. In addition to the profiles, other summary and detailed census data are available especially through the U.S. Census Bureau’s American FactFinder
How_ACS_Works text [pdf]