U.S. Federal Route 50 runs east-west across Southern St. Louis County. Most of this is on the areas expressway system. This enters the county from Illinois on Interstate 255. In the southwestern portion of the county it runs along Interstate 44. U.S. Rt. 50 passes through the following towns in St. Louis County. Sunset Hills
U.S. Rt. 50 is multi-plexed in St. Louis County. Interstate 255, from the Illinois/Missouri State Line to South County.