From the Ancestry.com Blog:
What do Colorado, Ohio, Pennsylvania, Tennessee, Vermont, and Virginia all have in common? Early this morning, fully indexed census records for each those six states were put online. All images for the 1940 census have been online and fully available to you since the first week of April. But, the completion of these indexes now allows you to search over 39 million records in ten states and the District of Columbia.
Updated Status List of Name Indexing for All 50 States and D.C.
Direct to 1940 U.S. Census on Ancestry.com