Internet Archive has announced that a publicly accessible digital copy of the complete 1930 United States Census – the largest, most detailed census released to date – is available free of charge at http://www.archive.org/details/1930_census. Previously, 1930 Census records were accessible only through microfilm, or subscription services in which select portions of data are provided for a fee.

http://blog.archive.org/2010/12/22/1790-1930-u-s-census-records-available-free/