The Census Bureau's National Processing Center (NPC) in Jeffersonville, IN, maintains copies of the 1910 to 2010 census records. Records from the censuses of population and housing are publicly accessible 72 years after each decennial census' "Census Day." The most recent publicly available census records are from the 1940 census, released April 2, 2012.
After the 72 years have passed, the National Archives and Records Administration (NARA) is responsible for making the records publicly available for viewing or purchase. Therefore, records from the 1950 census will be released on April 1, 2022.
Individuals may request their own records (before they are publicly available) via the Census Bureau's Age Search service. This service provides individual information from censuses that are still protected by the 72-year rule, but only to the named person, his or her heirs, or legal representatives. There is a Congressionally-mandated fee for this service. Individuals interested in requesting a search of their personal census records must complete a form BC-600 [PDF 142k], Application for Search of Census Records (form BC-600sp [PDF - 156k], Solicitud Para Busqueda De Registros Censales).
The National Archives released the 1940 population census records on April 2, 2012. The digital images are accessible at NARA facilities nationwide through its public access computers as well as on personal computers via the internet.
Only the population schedules are available from 1940. Housing and agriculture schedules were destroyed after data were collected, and therefore, were not microfilmed for eventual public release.
The 1930 census became available on April 1, 2002, as National Archives and Records Administration microfilm publication T626, Fifteenth Census of the United States, 1930 (2667 rolls).
The 1930 census and all existing Soundex indexes are available at the National Archives Building, 700 Pennsylvania Ave., NW, Washington, DC 20408-0001; the Archives' regional facilities around the country; many public libraries; and for a fee at online commercial genealogy sites.
For more information about using the 1930 census to complete your genealogical research, visit the National Archives' 1930 Federal Population Census website.