In the U.S., when a work was published is crucial in determining how long copyright lasts. In some cases, it is even more important to see if the registration was renewed. Cornell University created a chart to help understand when works will fall into the public domain. The basic idea for works published in the U.S. is the following:
- Works published between 1923 and 1963 have to have both a notice (or a © somewhere on the work) and renewal after 28 years (check the Copyright Catalog for renewals made after 1978 or Penn State's Archive of Copyright Registration and Renewal Records for things renewed before 1978:
- With Notice
- Renewed: 95 years after publication
- Not Renewed: 28 years after publication
- Without Notice: Public Domain since publication.
- Works published between 1964 and 1977 have to have notice, but renewal was automatic.
- With notice: 95 years after publication
- Without notice: Public Domain since publication.
- Works published between 1978 and 1989 have to have registration within five years of publication.
- With registration within 5 years: Author's Life + 70 years
- Without registration within 5 years: Public Domain since publication.
- Works published after 1989 do not need be registered, have notice, or be renewed. They have copyright duration of Author's Life + 70 years.
The rules are more complicated, but this is the basic jist of it. I recommend you look at the aforementioned chart made by Cornell for more exact rules.
It is important to know that sound recordings are different from compositions and that the law about this has actually changed in October of 2018 with the signing of the Music Modernization Act. The aforementioned chart will eventually be updated, but keep this in mind if you are trying to figure out whether a sound recording is in copyright or not. Information about sound recordings can be found in the "Sound Recordings" tab on the left.