The Little Arkansas River is a river in the central Great Plains of North America. A tributary of the Arkansas River, its entire 123-mile length lies within the American state of Kansas. The river originates in central Kansas in the Smoky Hills region of the Great Plains. Its source lies in extreme south-central Ellsworth County immediately north of Geneseo, Kansa…The Little Arkansas River is a river in the central Great Plains of North America. A tributary of the Arkansas River, its entire 123-mile length lies within the American state of Kansas. The river originates in central Kansas in the Smoky Hills region of the Great Plains. Its source lies in extreme south-central Ellsworth County immediately north of Geneseo, Kansas. From there, the river flows generally south-southeast along the border between the Arkansas River Lowlands to the southwest and the McPherson Lowlands to the northeast. It joins the Arkansas River immediately northwest of downtown Wichita, Kansas.