Red River of the South

The Red River of the South is a major river flowing east from the Texas Panhandle through the southern Great Plains into Louisiana, where it joins the Mississippi River. Parts of its course form the Texas–Oklahoma border.

Mississippi River basin: The drainage basin whose waters ultimately flow into the Mississippi River and its outlets. The Red River is one of the Mississippi basin’s major tributary systems.
Denison Dam: A dam on the Red River that impounds Lake Texoma on the Texas–Oklahoma border. It regulates flows and creates a major reservoir on the river.
Red Beds: Sedimentary rock layers colored red by iron oxides, widespread in parts of the southern Great Plains. Eroded red sediments help give the river its characteristic color and name.
Red River Compact: An interstate agreement governing allocation of the Red River’s waters among Texas, Oklahoma, Arkansas, and Louisiana. The compact addresses competing demands for water across the river basin.
Caddo Lake: A natural lake and wetland complex on the Texas–Louisiana border, connected to the Red River system. Its wetlands reflect the river basin’s distinctive lower-course landscape.
Texas–Oklahoma border: The boundary separating the U.S. states of Texas and Oklahoma. The river forms a substantial stretch of this state boundary.
Lake Texoma: A reservoir formed by Denison Dam on the Red River along the Texas–Oklahoma border. The reservoir stores water and moderates downstream river flows.
Southern Great Plains: The semiarid grassland region of the central United States south of the High Plains. The river’s headwaters and upper course lie within this region.
Water rights: Legal rights and rules governing the use, allocation, and control of water. Interstate disputes over the river have centered on who may use its water.
Great Raft: A massive accumulation of fallen timber that historically obstructed the Red River in Louisiana. The raft blocked navigation and prompted major efforts to clear the river.

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Adams–Onís TreatyBroader topic: The treaty’s boundary followed it westward from the Sabine River.