American copyright once ran on a split term: an initial period of protection followed by a second, "renewal" period that the owner had to affirmatively claim before the first term lapsed. Because most owners never filed, the renewal requirement quietly deposited the majority of the twentieth century's registered works into the public domain — the largest accidental enrichment of the commons in the nation's history. This UpLaw article reconstructs that system from the 1909 Copyright Act through the 1976 recodification, the 1992 automatic-renewal amendment, and the 1998 Sonny Bono term extension, and it explains the Supreme Court cases — Fred Fisher, Miller Music, De Sylva, and Stewart v. Abend — that still decide who owns a pre-1978 renewal copyright. It maps the constitutional battles over term extension and foreign restoration in Eldred v. Ashcroft and Golan v. Holder, walks through filing a renewal on Form RE, distinguishes renewal from the separate right to terminate transfers, and supplies a repeatable decision tree for the question that draws most readers here: is this old work free to use? The operative headline, as of 2024, is that everything published in the United States before 1929 belongs to everyone.