Public Domain Music and the Loch Ness Monster
It is the nature of our universe that it is impossible to prove that something does not exist. Find the Loch Ness Monster and we have proof that Nessie really does exist. We can be pretty darn sure, even virtually certain, that no gigantic creature has ever lived in Loch Ness Lake. But absence of existence cannot be proven. And so goes the problem with the public domain status of many songs.
Works published in 1922 or earlier were granted a maximum of 75 years of copyright protection by the US Congress. All possible copyright protection expired in 1998 for all musical works published from the Beginning of Time up through 1922. In 1999, the Sonny Bono Copyright Extension Act increased copyright protection to 95 years, so 1923 published works will enter the public domain in 2019, 21 years after 1922 works became PD.
Please carefully note that in the USA copyright protection term begins when a song is PUBLISHED, not when it is written. We know that "Old MacDonald Had a Farm" existed in 1921 because the title appears on the Song List of the 1921 Kiwanis Club Convention program. But knowing that a song existed in 1921 does not necessarily mean it is in the public domain. A PD proof is found on page 84 of "Tommy's Tunes", a soldier's song book published in 1917, where the song "Ohio" is published with music and words "Old Macdougal had a farm in Ohio-i-o".
E-yi-o-hi-o! We can now PROVE that "Old MacDonald" was indeed PUBLISHED at least as early as 1917. All possible copyright protection has expired, no one can claim ownership of the song, and no one can collect any royalties. "Old MacDonald Had A Farm" is PD in the USA.
If you can show that a song was published in sheet music or a book or a periodical with a copyright date or 1922 or earlier, it is pretty easy to PROVE that all possible copyright protection has expired. Conversely if it is known that a song was written after 1923, one can be quite confident that someone, somewhere, out there claims to own the song (even if the claim is not valid . . . but that's another day's story).
If you cannot find out who wrote the song or when, uh-oh! A song is in the public domain because ALL POSSIBLE COPYRIGHT PROTECTION has expired. You can prove a song is PD by finding a 1922 or earlier publication. But if the origin of a song is unknown, just like the Loch Ness Monster, there is no way to prove that a song was NEVER published before 1923. We can tell you where we have looked; we can tell you where it cannot be found. But we cannot tell you that a PD publication does not exist.
So we often just have to tell people that the public domain status of a song is NOT KNOWN. Some go away mad, some go away sad, and a few even scream at us. We have a PD proof in our library for thousands of songs and musical works, and we acquire and catalog more PD books and sheet music most every day. But for some songs the only answer we can give is we are looking . . . and looking . . . and looking . . .