Arkansas River, large tributary of the Mississippi River, rising in the Sawatch Range of the Rocky Mountains near Leadville in central Colorado, U.S., and flowing generally east-southeastward for 1,460 miles (2,350 km) through Kansas, Oklahoma, and Arkansas before entering the Mississippi 40 miles (64 km) northeast of Arkansas City, Ark. It has a total fall of 11,400 feet (3,475 m), and its drainage basin covers 161,000 square miles (417,000 square km). |