The Old Gray Mare is an old folk song, more recently regarded as a children's song.
Some authors have said that the song originated based upon the performance of the horse Lady Suffolk, the first horse recorded as trotting a mile in less than two and a half minutes. It occurred on 4 July 1843 at the Beacon Course racetrack in Hoboken, New Jersey, when she was more than ten years old. One author attributed the song to Stephen Foster, although the composer is usually listed as unknown. The archival evidence, however, is that the song originated a few decades later in the nineteenth century as a campaign ditty, composed as an epithet of Baltimore mayor Ferdinand Latrobe by Democratic Party (United States) political operative and appointee Thomas Francis McNulty. The book The Gallant Gray Trotter featured Lady Suffolk.
Popular early recordings were by Prince's Orchestra (1917) and by Arthur Collins and Byron Harlan (1918).
Bing Crosby included the song in a medley on his album On the Sentimental Side (1962).
The song was featured in an episode of The Simpsons titled "Krusty Gets Kancelled", where an old man sings the first verse of the song with his pants down and became a hit on television. In the later episode "Moms I'd Like to Forget" the 4th graders including Bart sing a parody of the song, which the 5th graders declare as a dishonor to the original.