The 1940 census images will be released on 2 April 2012 and those used to indexed census records are in for a challenge.
My 1940 census webinar discusses ways to find addresses to help with 1940 census work, finding the correct enumeration district, using the enumeration district maps, and more.
The webinar (including handout) can be downloaded for $4.00. Get ready for your 1940 census search.
