The National Archives and Records Administration opened the 1940 U.S. Federal Census on April 2, 2012 —  collection now available to the public.

Ancestry received the census, and quickly began uploading census images to their site so the public can now browse them. All states should be viewable by this Friday afternoon.
Initially, the collection will remain a browse-only collection. This means one can scroll through the pages of the census districts much like someone looks at a microfilm or a book. At the same time, Ancestry will be working behind the scenes to create an index of the census that will eventually allow persons to search for their family members by name as they currently can with all other censuses on Ancestry.com.

 Note:  the 1940 U.S. Federal Census will be accessible  free of charge throughout 2012 on Ancestry.com.

Ancestry.com hosts the largest collection of family history records on the web.  Learn details about your family's lives and build a family tree online. There are YouTube clips to guide individuals on how to navigate the 1940 records.