The Dauphin Island Bridge, formally the Gordon Persons Bridge, carries a 3-mile (4.8 km), two-lane section of Alabama State Route 193 from mainland Mobile County, Alabama across the Gulf Intracoastal Waterway to Dauphin Island. The natural channel followed by the Gulf Intracoastal Waterway at this location is Pass Aux Herons. The bridge separates the Mississippi Sound on the west from Mobile Bay on the east.