Ancestry.com has announced that its 1940 census index is now complete—you can search it for ancestors in all 48 US states (Alaska and Hawaii hadn’t yet become states in 1940) plus territories. Ancestry.com’s index will be free to search through 2013.
FamilySearch isn’t far behind. Its volunteer-created index is almost complete, and only 19 states’ indexes remain to be added to the site’s search. The 1940 census index is free on FamilySearch.org as well as its 1940 Census Community Project partners Archives.com and findmypast.com.