Missouri River

longest river · Rocky Mountains · North America

Starts in the Rockies. The Missouri River begins high in the Centennial Mountains of southwestern Montana, in the Bitterroot Range of the Rocky Mountains, where cold mountain streams first join together.

Flows across half a continent. From its mountain home, the Missouri travels east and south for 2,341 miles before joining the Mississippi River north of St. Louis, Missouri, passing through or alongside ten U.S. states and two Canadian provinces.

Drains a massive area. The river's watershed covers more than 500,000 square miles of land, collecting water from a semi-arid region and carrying it all downstream in one mighty flow.

Longer than its parent river. Even though the Missouri is officially a tributary of the Mississippi, it is actually slightly longer and carries about the same amount of water as the Mississippi does.

Part of a giant system. When you combine the Missouri with the lower Mississippi River, they create the world's fourth-longest river system, second only to the Nile, Amazon, and Yangtze Rivers.