U.S. Federal Route 31 is a north-south highway through the center of St. Joseph County. Around a portion of the South Bend Area, this highway is a expressway. Some areas call it "BY-PASS" U.S. Rt. 31. Portions of the old alignmet is known as BUSN. U.S. Rt. 31. U.S. Rt. 31 passes through the following towns in St. Joseph County. South Bend
U.S. Rt. 31 is multi-plexed in St. Joseph County. U.S. Rt. 20, in South Bend.