State Highway 75 is a Texas state route remnant of the old U.S. Route 75. State Highway 75 retained the number as a state highway when Interstate 45 supplanted U.S. Route 75 south of Dallas except in Dallas, where old U.S. Route 75 is now State Highway 310, and through Ferris, Palmer, Ennis, and Corsicana, where the old highway is signed as Business Route I-45. This route was designated in 1987.