Guide to U.S. Copyright

Chart detailing how long it takes various artistic works to go into the public domain in USA . Immensely useful and depressing. Also, how to tell if a copyright is renewed. This is a very important task, because works published between 1923 and 1964 whose copyright have NOT been renewed (and only 15% of these copyrights have been renewed) automatically fall into public domain. The ambiguity lies in determining dates of original publication as well as figuring out which date applies.