This undated image provided by the National Archives and Records Administration shows a form used in the 1940 Census. The 1940 Census will be released to the public on Monday, April 2, 2012. While a name index will not be immediately available to search, tens of thousands of researchers across the country are expected to go on a massive genealogical hunt through the digitized records for details on 132 million people. (AP Photo/National Archives and Records Administration)
The 1940 census records were released Apr. 2, with more than 21 million people alive in the U.S. and Puerto Rico.