The Arkansas River is a major tributary of the Mississippi River. The Arkansas generally flows to the east and southeast, and traverses the states of Colorado, Kansas, Oklahoma, and Arkansas.
At 1,469 miles (2,364 km) it is the sixth longest river in the United States, the second-longest tributary in the Mississippi-Missouri system, and the 45th longest river in the world. Its origin is in the Colorado Rockies in Lake County near Leadville, and its outlet is at the historic site of Napoleon, Arkansas. The Arkansas River drainage basin covers nearly 195,000 sq mi (505,000 km²). (See watershed maps: 1) In terms of volume, the river is smaller than both the Missouri and Ohio, with a mean discharge of 8,460 ft³/s (240 m³/s).

General description

Main article: McClellan-Kerr Arkansas River Navigation System Riverway commerce
Many nations of Native Americans lived near or along the Arkansas in its 1450 mile (2334 km) stretch, but the first Europeans to see the river were members of the Coronado expedition on June 29, 1541. Also in the 1540s Hernando de Soto discovered the junction of the Arkansas with the Mississippi. The name "Arkansas" was first applied by Father Jacques Marquette, who called the river Akansa in his journal of 1673.
From 1819 the Adams-Onís Treaty set the Arkansas as part of the frontier between the United States and Spanish Mexico, which it remained until the annexation of Texas and Mexican-American War in 1846.
Later, the Santa Fe Trail followed the Arkansas through much of Kansas except for the Cimarron Cutoff from Cimarron, Kansas to Cimarron, New Mexico via Cimarron County, Oklahoma along the Cimarron River.

Watershed trails
The Arkansas River, in central Colorado, provides some of the best brown trout fishing in the west. The Arkansas starts just north of Leadville Colorado. The first 150 miles of the river, from Leadville to Pueblo, is prime trout water. Conditions vary widely along this section so the river is broken up into 4 sections; Leadville to Buena Vista, Buena Vista to Salida, Salida to Canon City, Canon City to Pueblo. The Arkansas drops over 5000 feet in elevation over this 150 mile stretch from Leadville to Pueblo. Seasons are quite different on each of these sections. The Arkansas through Canon City may be experiencing Spring conditions, while the Leadville area is still full blown winter. Due to this sudden change in climate and elevation, fishing conditions vary depending on which section of the river you plan to fish, and at what time of year you plan to be there. The Arkansas boasts high catches of browns and rainbows to 20 inches. Browns dominate the fishery.