The Neosho River is a tributary of the Arkansas River in eastern Kansas and northeastern Oklahoma in the United States. Its tributaries also drain portions of Missouri and Arkansas. The river is about 460 mi (740 km) long. Via the Arkansas, it is part of the Mississippi River watershed. In Kansas, the Neosho is joined by the Cottonwood River in Lyon County.
The Neosho River is a tributary of the Arkansas River in eastern Kansas and northeastern Oklahoma in the United States. Its tributaries also drain portions of Missouri and Arkansas. The river is about 460 mi (740 km) long. Via the Arkansas, it is part of the Mississippi River watershed.