As of January 1, 2021, works published in the U.S. in 1925 are now in the public domain, most notably F. Scott Fitzgerald's The Great Gatsby (I checked Gutenberg.org but it's not there yet). Duke's Center for the Study of the Public Domain has a list of other well-known works now free for the taking, adapting, and extending.
Works from 1925 were supposed to go into the public domain in 2001, after being copyrighted for 75 years. But before this could happen, Congress hit a 20-year pause button and extended their copyright term to 95 years.2 Now the wait is over.
In 2021, there is a lot to celebrate. 1925 brought us some incredible culture. The Harlem Renaissance was in full swing. The New Yorker magazine was founded. The literature reflected both a booming economy, whose fruits were unevenly distributed, and the lingering upheaval and tragedy of World War I. The culture of the time reflected all of those contradictory tendencies. The BBC's Culture website suggested that 1925 might be "the greatest year for books ever," and with good reason. It is not simply the vast array of famous titles. The stylistic innovations produced by books such as Gatsby, or The Trial, or Mrs. Dalloway marked a change in both the tone and the substance of our literary culture, a broadening of the range of possibilities available to writers, while characters such as Jay Gatsby, Hemingway's Nick Adams, and Clarissa Dalloway still resonate today.
How will people celebrate this trove of cultural material? The Internet Archive will add books, movies, music, and more to its online library. HathiTrust will make tens of thousands of titles from 1925 available in its digital repository. Google Books will offer the full text of books from that year, instead of showing only snippet views or authorized previews. Community theaters can screen the films. Youth orchestras can afford to publicly perform, or rearrange, the music. Educators and historians can share the full cultural record. Creators can legally build on the past—reimagining the books, making them into films, adapting the songs.