U.S. Route 431 (US 431), internally designated by the Alabama Department of Transportation (ALDOT) as State Route 1 (SR 1), is a major north–south state highway across the eastern part of the U.S. state of Alabama. Although US 431's south end is in Dothan, SR 1 continues south for about 13 miles (21 km) along US 231 to the Florida state line.