The Washita River forms in eastern Roberts County, Texas () near the town of Miami, Texas in the Texas Panhandle. The river is 295 miles long and terminates into Lake Texoma in Johnston County (also Bryan County and Marshall County - 33°55′ N 96°35′ W), Oklahoma and the Red River.

It crosses Hemphill County, Texas and enters Oklahoma in Roger Mills County. In Oklahoma it cuts through the Oklahoma Counties of: Roger Mills, Custer, Washita, Caddo, Grady, Garvin, Murray, Carter, and Johnston. Lake Texoma is the border between Bryan County and Marshall County.

Along its path the Washita River contains the Foss Reservoir. Small tributaries hold the waters of Fort Cobb Lake, Lake Chickasha, and Arbuckle Reservoir. The river passes through or near the Oklahoma towns of Cheyenne, Clinton, Anadarko, Chickasha, and Pauls Valley.

The river bisects the heart of the Anadarko Basin, according to the USGS the Anadarko Basin is the fifth largest natural gas formation area discovered in the United States.

See also

• List of counties in Oklahoma