Copyright was designed to provide for the protection of an author's work for a fixed amount of time. The original statute provided fourteen years of copyright protection.
Current copyright law provides protection for the life of the author, plus 70 years for an individual. Corporate entities receive over 100 years of protection. Congress has extended the length of copyright many times over the years. This variance presents a challenge when trying to determine the copyright status of older works Fortunately, there are some good resources to help navigate the maze of copyright duration. Cornell University's copyright duration and public domain chart is updated annually to provide copyright status guidance on various types of materials. The American Library Association's digital copyright slider tool may also be helpful as a starting point.
Consult the Public Domain
section of this guide for information on materials that are not subject
to copyright protection, including those with expired copyrights.