Narrower Terms (13)

• Arkansas River Valley
• Canadian River Valley
• Colorado River Valley (Colo.-Mexico)
• Connecticut River Valley
• Delaware River Valley (N.Y.-Del. and N.J.)
• ▶ Mississippi River Valley
• Missouri River Valley
• Ohio River Valley
• Potomac River Valley
• Rio Grande Valley (Colo.-Mexico and Tex.)
• ▶ Snake River Valley (Wyo.-Wash.)
• Susquehanna River Valley
• Tennessee River Valley