In the United States, the copyright law causes all copyrighted works which have reached the end of their term of copyright protection to fall into the public domain on January 1 of the appropriate year.

Due to the accession by the United States to the Berne Convention (Berne Union treaty), the U.S. originally changed its laws to have all works created by an author fall out of copyright (into the public domain) at the same time, January 1, 50 years after they died, or either 75 years after publication or 100 years after creation, whichever is shorter, if the author was not a natural person or was a collective work or work for hire.

This was later changed as a result of the Sonny Bono Copyright Term Extension Act which increased protections for copyright holders by 20 years to harmonize with the WIPO Copyright Treaty and the equivalent extension made to the 1993 revisions to the Berne Convention.

As a result of these changes, in the case of a work created by an individual, the work goes into the public domain on January 1, 70 years after the author dies. Where the work is a joint effort of two or more authors, it goes into the public domain on January 1, 70 years after the death of the last surviving joint author.

In the case of a work made for hire, a pseudononymous work, a collective work (such as an Encyclopedia like this) the work goes into the public domain on January 1, 95 years after the date of first publication, or 120 years after creation, whichever is shorter.