In the United States, under U.S. copyright law, works published in 1925 and earlier are now in public domain. One can publish them or use them without securing copyright permission. In case you are wondering about the specifics, the Copyright Term Extension Act (passed in 1998) gave works published from 1923 through 1977 a 95-year term limit. They enter public domain on January 1 after the conclusion of the 95th year.
It gets a little complicated because anything copyrighted before 1977 had only a 28-year protection. The copyright had to be renewed in the 28th year, or the book went into public domain. It is estimated that as much as 85% of such properties were not renewed and are now in public domain. But determining that for certain can be quite a task!
By the way, this happens not only with books but anything under copyright like films and music.
A few notable titles are on this year’s list:
F. Scott Fitzgerald, The Great Gatsby
Virginia Woolf, Mrs. Dalloway
Ernest Hemingway, In Our Time (his first novel)
Theodore Dreiser, An American Tragedy
Sinclair Lewis, Arrowsmith
Agatha Christie, The Secret of Chimneys
Aldous Huxley, Those Barren Leaves
W. Somerset Maugham, The Painted Veil
Edith Wharton, The Writing of Fiction
Note that while these books are in public domain, you can’t slap your name on them and claim you wrote them. There’s a word for that: plagiarism. However, if you wanted to create a derivative story like The Great Gatsby Goes to Mars or Mrs. Dalloway Gets a Job at Burger King, you can certainly do so without getting permission first.
On a trivia note, there was an awful book first published in 1925 as well. Mein Kampf by Adolf Hitler. Since there doesn’t appear to be a record of a copyright renewal in 1953, that work is in the public domain. But if there had been a question, it has been 95 years and is no longer under copyright protection.
And if you want to plan ahead? In 2022 the following are on the list to slide into the public domain:
Agatha Christie, The Murder of Roger Ackroyd
Arthur Conan Doyle, The Land of Mist
Ernest Hemingway, The Sun Also Rises
Franz Kafka, The Castle
T. E. Lawrence, Seven Pillars of Wisdom
A. A. Milne, Winnie-the-Pooh
Dorothy L. Sayers, Clouds of Witness
Ruth Plumly Thompson, The Hungry Tiger of Oz