The Arkansas River (Pawnee: Kícka ) is a major tributary of the Mississippi River. The Arkansas generally flows to the east and southeast as it traverses the U.S. states of Colorado, Kansas, Oklahoma, and Arkansas. The river's initial basin starts in the Western United States in Colorado, specifically the Arkansas River Valley where the headwaters derive from the snowpack in the Collegiate Peaks. Then it flows east into the Midwest via Kansas, and finally into the South through 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 Rocky Mountains in Lake County, Colorado, near Leadville. In 1859 placer gold was discovered in the Leadville area bringing thousands seeking to strike it rich, however the easily recovered placer gold was quickly exhausted. The Arkansas River's mouth is at Napoleon, Arkansas, and its drainage basin covers nearly 170,000 sq mi (440,300 km²). In terms of volume, the river is much smaller than both the Missouri and Ohio Rivers, with a mean discharge of roughly 41,000 cubic feet per second (1,200 m³/s).

Arkansas (ⁱ/ˈɑrkənsɔː/ AR-kən-saw) is a state located in the Southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states (N: Missouri; E: Tennessee, Mississippi; S: Louisiana; SW: Texas; W: Oklahoma), and its eastern border is largely defined by the Mississippi River. Its diverse geography ranges from the mountainous regions of the Ozarks and the Ouachita Mountains, which make up the U.S. Interior Highlands, to the eastern lowlands along the Mississippi River. Arkansas is the 29th most extensive and the 32nd most populous of the 50 United States. The capital and most populous city is Little Rock, located in the central portion of the state.

The name “Arkansas” derives from the same root as the name for the state of Kansas. The Kansa tribe of Native Americans are closely associated with the Sioux tribes of the Great Plains. The word “Arkansas” itself is a French pronunciation (“Arcansas”) of a Quapaw (a related “Kaw” tribe) word, akakaze, meaning “land of downriver people” or the Sioux word akakaze meaning “people of the south wind”. The pronunciation of Arkansas was made official by an act of the state legislature in 1881, after a dispute between two U.S. Senators from Arkansas. One wanted to pronounce the name /ɑrˈkænzəs/ ar-KAN-zəs and the other wanted /ˈɑrkənsɔː/ AR-kən-saw.