Billy the Kid is a 1938 ballet written by the American composer Aaron Copland on commission from Lincoln Kirstein. It was choreographed by Eugene Loring for Ballet Caravan. Along with Rodeo and Appalachian Spring, it is one of Copland’s most popular and widely performed pieces. The ballet is most famous for its incorporation of several cowboy tunes and American folk songs and, although built around the figure and the exploits of Billy the Kid, is not so much a biography of a notorious but peculiarly appealing desperado as it is a perception of the pioneer West, in which a figure such as Billy played a vivid role.[1]

It was premiered on 16 October 1938[2] in Chicago by the Ballet Caravan Company, with pianists Arthur Gold and Walter Hendl performing a two-piano version of the score. The first performance of Billy the Kid in New York City occurred on 24 May 1939, with an orchestra conducted by Fritz Kitzinger.

(from Wikipedia)

Billy The Kid, Ballet Suite
By Aaron Copland
Composed in 1938