"For U.S. books published between 1923 and 1963, the rights holder needed to submit a form to the U.S. Copyright Office renewing the copyright 28 years after publication. In most cases, books that were never renewed are now in the public domain. Estimates of how many books were renewed vary, but everyone agrees that most books weren't renewed. If true, that means that the majority of U.S. books published between 1923 and 1963 are freely usable.
" How do you know? The renewal copyright records have traditionally been scattered and hard to access, but Google - with the help of Project Gutenberg and the Distributed Proofreaders painstakingly typed in every word - has just released a single database as a freely downloadable XML file
posted to MetaFilter by stbalbach
at 8:23 AM on June 25, 2008