The Saline River, also known as Saline Creek, is a 202-mile-long (325 km) tributary of the Ouachita River in the south central portion of the U.S. state of Arkansas. It is the longest river that flows entirely within the state of Arkansas. The Saline River begins in the eastern foothills of the Ouachita Mountains in Saline and Garland counties. The river has four headwater tributaries, the South Fork, the Middle Fork, the Alum Fork, and the North Fork, which merge northwest of the city of Benton.