Okay, we know books published in the U.S. before 1923 are probably in public domain. And the copyright of books published after 1963 was automatically renewed. But books published in the forty years between those two dates might or might not be in public domain, depending on whether the copyright holder renewed the copyright.

Books published in the U.S. during those years received an initial copyright term of 28 years, meaning the if the work was originally published in 1932, for example, its copyright would expire in 1960. But the copyright holder could renew the copyright for another 47 years in the final year of its first term (that is, in the 28th year). And, further complicating matters, anything that was under copyright in 1998 had its term extended for an additional 20 years. That means that a book published in 1932 is either in public domain or under copyright until 2027.

That’s a big difference, so which is it? To find out whether the copyright of a book from the 1923-1963 period was renewed, one used to have to commission a copyright search through the copyright office, which generally costs about $75. But now some institutions are putting the copyright database online, so if you’re planning to put some classic text on your website, and you want to be sure you’re legal, you can research it here: