The Missouri River is a river in the Central and Mountain West regions of the United States. The nation's longest, it rises in the eastern Centennial Mountains of the Bitterroot Range of the Rocky Mountains of southwestern Montana, then flows east and south for 2,341 miles (3,767 km) before entering the Mississippi River north of St. Louis, Missouri. The river drains semi-arid watershed of more than 500,000 square miles (1,300,000 km2), which includes parts of ten U.S. states and two Canadian provinces. Although a tributary of the Mississippi, the Missouri River is slightly longer and carries a comparable volume of water. When combined with the lower Mississippi River, it forms the world's fourth-longest river system.
The Missouri River in Montana
Holter Lake, a reservoir on the upper Missouri River
The Missouri in North Dakota, which was the furthest upstream that French explorers traveled on the river
The Yellowstone River, the fifth longest tributary of the Missouri, which it joins in North Dakota
The Bitterroot Range is a mountain range and a subrange of the Rocky Mountains that runs along the border of Montana and Idaho in the northwestern United States. The range spans an area of 24,223 square miles (62,740 km2) and is named after the bitterroot, a small pink flower that is the state flower of Montana.
Part of the Bitterroot Range in Montana, looking north from El Capitan peak
