"U.S. Route 231 is a parallel route of U.S. Route 31. It currently runs for 912 miles from St. John, Indiana, at U.S. Route 41 to south of U.S. Route 98 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."