"She Caught the Katy (And Left Me a Mule to Ride)" is an upbeat blues written by Taj Mahal and James Rachell. It was first released on Taj Mahal's 1968 album The Natch'l Blues, and is one of Mahal's most famous compositions.
The song has since become a blues standard and has been covered many times. It was used on the soundtrack for the 1980 movie The Blues Brothers (the song plays over the opening credits as Jake Blues leaves prison). According to John Belushi's widow, it was Belushi's favorite blues song.
The "Katy" refers to the Missouri–Kansas–Texas Railroad.