Every ten years the U.S. Census Bureau undertakes the only comprehensive counting of the entire population. Mandated by the Constitution (article I, section 2) census data are available for every census from 1970 onward. For privacy reasons, the actual names and individual responses are unavailable until 72 years later. In April 2012 the 1940 census enumeration records became available to the general public.
To access the enumeration records you can visit these three places:
1) The National Archives and Records Administration (NARA) web site: http://1940census.archives.gov/
NARA is partnering with Archives.com to make the scans and indexing of the 1940 census available.
2) Archives.com – http://www.archives.com/1940census
This is the free Archives.com web site.
3) Ancestry Library Collection
This is the subscription-based version of Archives.com to which Penrose Library subscribes via ProQuest.
If it is Census data you want, here are several ways to access it:
1. We have it in print under SuDocs number C 3.940-5:
This information is covered in a Research Guide: http://libguides.du.edu/census
2. The University of Virginia Library has a very nice historical census browser:
3. Our Social Explorer database provides historical census statistics:
This allows for generation of tabular data and beautiful maps as well.