The Kansas River is a tributary of the Missouri River located in the central United States. It is formed by the confluence of the Republican and Smoky Hill rivers near Junction City, Kansas. Two of its major tributaries are the Neosho River and the Osage River. The Neosho River is a tributary of the Arkansas River that flows through Kansas, Oklahoma, and Arkansas. It is approximately 545 miles long and is known for its scenic beauty. The Osage River is a tributary of the Missouri River that flows through Missouri and Kansas. It is approximately 645 miles long and is known for its diverse wildlife.