Folks on this list should be aware that the term of copyright in the U.S. for pre-1978 works has been raised from 75 to 95 years. Twenty more years of raking it in for Disney and the Gershwin Trust.
As I understand the new law (but as usual on internet discussion lists, this is not legal advice, nothing in this post establishes a lawyer-client relationship, in fact I'm not even a lawyer, etc.), U.S. copyrights which were secured in 1922 or earlier have expired. Copyrights from 1923 will expire on January 1, 2019, assuming the Gershwin trust and Disney don't make a few strategic campaign contributions 18 or so years from now and get another extension.