"Happy Trails" is a song by Roy Rogers and his wife Dale Evans, known as the theme song for both The Roy Rogers Show on radio and The Roy Rogers Show on television, in which they starred.
It was written by Evans and always sung by the duo over the end credits of those programs.
[1] In 1951, Foy Willing had written a song titled "Happy Trails" for the Republic Pictures movie, Spoilers of the Plains, starring Roy Rogers with Foy Willing and the Riders of the Purple Sage.
Subsequently, the first three notes of Foy's song and the title were used by Dale Evans in writing her version of "Happy Trails" for both the original The Roy Rogers Show and the short-lived The Roy Rogers and Dale Evans Show, which aired on ABC in 1962.
Dale's is the version that is popularly played and sung today, albeit without giving credit to Foy Willing.