U.S. Route 231 or U.S. Highway 231 (US 231) is a parallel auxiliary U.S. route of US 31. It runs for 912 miles (1,468 km) from St. John, Indiana, at US 41 to US 98 Business in downtown Panama City, Florida.
One of its most notable landmarks is the William H. Natcher Bridge, a nearly mile-long cable-stayed bridge that connects Rockport, Indiana, to Owensboro, Kentucky, spanning the Ohio River.
US 231 runs in the states of Florida, Alabama, Tennessee, Kentucky, and Indiana.