Saint Francis, river, c.470 mi (760 km) long, rising in the hills of SE Missouri and flowing S through NE Arkansas to join the Mississippi River near Helena, Ark. The river forms part of the Arkansas–Missouri border. Wappapello Dam (completed 1941), near Poplar Bluff, Mo., forms a reservoir. The river area is popular for recreational activities.
See more Encyclopedia articles on: U.S. Physical Geography