Missouri River Valley
The Missouri River Valley outlines where the Missouri River from its headwaters where the Madison, Jefferson and Gallatin Rivers flow together in Montana to its confluence with the Mississippi River in the State of Missouri. At 2,300 miles (3,700 km) long, the valley drains one-sixth of the United States. It is the longest river valley in North America. The valley in the Missouri River basin includes river bottoms and floodplains.