Narrower Terms (8)

• Ash Hollow (Neb.)
• Little Blue River Valley (Neb. and Kan.)
• Medicine Creek Valley (Neb.)
• Niobrara River Valley (Wyo. and Neb.)
• North Platte River Valley
• Platte River Valley (Neb.)
• Republican River Valley (Neb. and Kan.)
• South Platte River Valley (Colo. and Neb.)