Blue Mule is based on the Bill Monroe song Molly And Tenbrooks. The Monroe song is an arrangement of a Kentucky folk song which is thought to date from 1884. It describes a 4 mile race held at Churchill Downs in 1878 between Molly McCarthy and Ten Broeck. More information about Molly And Tenbrooks and a list of recordings of the song can be found on the Molly And Tenbrooks page.

In the Peter Rowan song the Blue Mule defeats both Molly and Tenbrooks.