Works published before 1923 have generally fallen into the public domain.
Works published after January 1, 1964, are almost always protected by copyright because the 1976 Copyright Act automatically renewed them.
The copyright status of any work published between 1923 and 1963 is very difficult to determine. Between those dates, a renewal registration was required to prevent the expiration of copyright. However, determining whether a work's registration was renewed is a challenge. Renewals received between 1950 and 1977 were announced and distributed only in a semi-annual print publication. The Copyright Office does not have a machine-searchable source for this renewal information, and the only public access is through the card catalog in their DC offices.
As a result, thousands of valuable genealogy books as well as many other works have never been republished because of concerns about copyrights. Now a new online database makes it much easier to determine whether a book's copyright has been renewed or not.
Project Gutenberg transcribed all the 1950-1977 renewals from the printed lists. Michael Lesk converted the transcribed information into a database format. Next, Stanford University provided online database servers, placed the data online, and then combined that data with the renewals for later years, which was already available on the Copyright Office's website. As a result, you now can quickly and easily find if any work was renewed in 1950 or later.
Note that this database covers only renewals, not original registrations, and is limited to books (Class A registrations) published in the US. Of course, any book printed before 1950 needed to be renewed some time between 1950 and 1977 to protect its copyright status. As a result, any book printed in the U.S. before those years and not listed in this database is now in the public domain.
This should be a great service for genealogy book publishers, family societies, and others. Thousands of genealogy books had copyright expiration dates between 1950 and1964, but publishers have been reluctant to republish them because the copyright renewal statuses have been unknown. This new database should eliminate many concerns, clearing the way for the republication of thousands of books.
The Stanford Copyright Renewal Database is available free of charge at http://collections.stanford.edu/copyrightrenewals/bin/page?forward=home.
My thanks to Mary D. Taffet for letting me know about this valuable new online resource.