The Missouri River (click here) drains one-sixth of the United States and encompasses 529,350 square miles. It flows 2,341 miles from its headwaters at the confluence of the Gallatin, Madison, and Jefferson Rivers in the Rocky Mountains at Three Forks, Montana, to its confluence with the Mississippi River at St. Louis, Missouri.
The basin is home to about 10 million people from 28 Native American tribes, 10 states (Colorado, Iowa, Kansas, Minnesota, Missouri, Montana, Nebraska, North Dakota, South Dakota, Wyoming), and a small part of Canada.
Precipitation in the basin varies from an annual mean of 40 inches in the interior highlands of the Missouri Ozarks to 10 inches in the dry upland plains of North and South Dakota, Wyoming, and Montana. The basin’s elevation drops from 14,000 foot peaks at its northwestern boundary to about 400 feet where it joins the Mississippi.
