The following is from Matthew Deighton at Ancestry.com:

With today’s addition of 12 states (18 million records) to the 1940 US Federal Census, Ancestry.com now has 37 states and Washington DC fully indexed and searchable on the site. All of the 1940 US Census will be free through 2013.

Number of records per state:

  • Alaska: 72,665
  • Arkansas: 1,955,176
  • Idaho: 526,673
  • Massachusetts: 4,325,657
  • Minnesota: 2,797,461
  • Missouri: 3,790,868
  • New Mexico: 534,334
  • North Dakota: 644,245
  • Oklahoma: 2,341,108
  • Rhode Island: 714,519
  • South Dakota: 643,766
  • Utah: 551,609