This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office) before January 1, 1929.

Steamboat Willie is a 1928 American animated short film directed by Walt Disney and Ub Iwerks. It marks Mickey Mouse and Minnie Mouse's first appearance in a distributed film. Mickey Mouse was created as a replacement for Oswald the Lucky Rabbit, created by the Disney studio but owned at the time by Universal Pictures, and when two silent films featuring the character failed to gain a distributor, Walt Disney decided instead to put him in a sound cartoon – perhaps inspired by The Jazz Singer. With music arranged by Wilfred Jackson and Bert Lewis, Steamboat Willie was one of the first cartoons with synchronized sound. The film received wide critical acclaim upon its release, and it has been preserved in the United States National Film Registry for its significance. The film enters the public domain under U.S. copyright law today (January 1, 2024), 95 years after its release in 1928.

Film credit: Walt Disney Studios

https://en.wikipedia.org/wiki/Template:POTD/2024-01-01