Mule Train (1950)

"GET A-LONG MULE!!! TO THE SONG-RAGE OF THE YEAR!"

A prospector discovers natural cement and suggests it should be used for a new dam. But this is the last thing the badmen of Trail End want, as they have a monopoly of the wagons needed to haul rocks to the site. A pretty sheriff notwithstanding, it's a job for a singing marshal.