The backbone of each Mickey short was a beloved, public domain song, with Mickey's motion synched to the beat (animators came to call this "mickey mousing"). In 1929, there was a *huge* crop of public domain music that anyone could use this way:
> Blue Danube, Pop Goes the Weasel, Yankee Doodle, Here We Go Round the Mulberry Bush, Ach Du Lieber Augustin, Listen to the Mocking Bird, A-Hunting We Will Go, Dixie, The Girl I Left Behind Me...
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