Over and over, genealogists have been told that the copyright has expired for all works published in the United States before 1928. In other words, if the work was published in the U.S. before January 1, 1928, anyone is free to republish excerpts or even the entire book without obtaining permission. That statement remains correct today. However, many genealogists are not aware that the overwhelming majority of all books published prior to 1964 are also free of copyright. That's "the overwhelming majority of all books" but not all of them.
Between 1928 and 1964, a renewal registration was required to prevent the expiration of copyright. If a work was first published before January 1, 1964, the owner had to file a renewal with the Copyright Office during the 28th year after publication. No renewal meant a loss of copyright. In other words, for all books published prior to 1964, the copyrights expired before January 1, 1992 IF THE COPYRIGHT WAS NOT RENEWED. However, a 1961 report from the U.S. Copyright Office estimates that 85% of the books never had the copyrights renewed. Therefore, those books are now public domain.
Major corporations generally had employees who monitored copyrights and made sure they were renewed. For instance, if you have a Disney comic book published during the 1940s, it probably is still under copyright because the Disney Corporation protected the company's copyrights and made sure the copyrights were renewed on time. However, the overwhelming majority of genealogy books that were self-published by individual genealogists probably did not have the copyrights renewed. The key word in that sentence is PROBABLY.
The laws changed for books published after January 1, 1964 and we can assume that all of those books are still under copyright today unless they were explicitly released to the public domain, according to U.S. copyright laws. The laws vary widely in other countries, however.
Determining whether a work's copyright registration has been renewed is a challenge but is not impossible. Renewals received by the Copyright Office after 1977 are searchable in an online database, but 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 the Copyright Office's D.C. offices.
In order to make these renewal records more accessible, Stanford University has created a Copyright Renewal Database. The database covers only renewals, not original registrations, and is limited to books (Class A registrations) published in the U.S. As a result, the Copyright Renewal Database is a big help but is not the definitive answer to all copyright questions concerning books published prior to 1964.
If you plan on using a work that was published after 1927, but before 1964, you should research the records of the Copyright Office to determine if a renewal was filed. You can research in person at the Copyright Office in Washington, D.C., or pay the Copyright Office to do a search for you $200.00 per hour with a 2-hour minimum (see http://www.copyright.gov/forms/search_estimate.html); or pay someone to perform the search for you.
You can read more about these copyright issues at:
and probably at a few dozen other web sites as well.