What musical was the Chattanooga chu chu?

The "Chattanooga Choo Choo" is a song from the musical "Sun Valley Serenade," which was released in 1941. The song, performed by the Glenn Miller Orchestra, became a major hit and is closely associated with the Big Band era. It features a catchy tune and lyrics celebrating train travel, particularly the route to Chattanooga, Tennessee. The song's popularity helped it become an iconic piece of American music history.