Arkansas

Arkansas, a major tributary of the Mississippi River, 2,334 km (1,450 mi) long. Rising in central Colorado, in the Sawatch Range of the Rocky Mountains, at an altitude of about 4,270 m (14,000 ft), the river flows generally east and forms a turbulent stream passing over rocky beds and through deep canyons such as the Royal Gorge. As it flows through the plains of Kansas, the river broadens to a wider, less turgid stream until it enters Oklahoma; at that point it receives two chief tributaries, the Cimarron and the Canadian rivers. Except for a large northern bend in Kansas, the Arkansas River follows a south-eastern course, merging with the Mississippi River above Arkansas City, Arkansas. The water levels of the river are extremely variable, and several dams have been built for flood control and irrigation and to create hydroelectric power; one of the most impressive, the John Martin Dam in south-eastern Colorado, was built in 1948. The Arkansas River Navigation System, completed in the early 1970s, made the river navigable to Tulsa, Oklahoma.