“Whoa Mule” belongs to an old family of mule songs — also known as “Buckin’ Mule” and “Kickin’ Mule” — whose verses and tunes have been traded back and forth since the nineteenth century. Gid Tanner recorded a version in the 1920s.
The song is a comic novelty piece. Its verses are a string of jokes and tall tales about a stubborn, bucking mule, and the song is built as much to show off fast, dexterous picking as to tell any story.
The song has long been a favorite of old-time string bands.