The Missouri River

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The 25 Longest Rivers in the World
The River as a Lifeline
The River as a Boundary
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The Missouri is the world's 15th-longest river at 2,341 miles. It flows from its source, at the Gallatin, Madison, and Jefferson Rivers in Montana, to the Mississippi River, at St. Louis.

The Missouri drainage area is 529,350 square miles, one-sixth of the entire United States. The basin is home to about 10 million people from 28 Native American tribes, 10 states, and a small part of Canada.

The Missouri is one of the most changed rivers in the U.S. Its many dams and reservoirs have created many lakes and stopped the free-flowing nature of the river, stopping flooding in many areas. Historically, the river has changed its course slightly many times in just the 200 years that Americans have been living nearby. In some places, the river has relocated more than 2,000 feet of soil. This is one reason that the Missouri is called the "Big Muddy" and the "Muddy Mo." ("Mo" is short for Missouri.)

The first Europeans to see the Missouri River were the Frenchmen Father Jacques Marquette and Louis Joliet, in 1673, when floating down the Mississippi. American explorers Meriwether Lewis and William Clark traveled the length of the Missouri River on their journey west with the Corps of Discovery.

Today, the river is used primarily for commerce, although some river cruises go up and down the "Muddy Mo."



 Facts About the Missouri River


2,341 miles


Gallatin, Madison, and Jefferson Rivers, Montana


Mississippi River, St. Louis

Countries Flows Through

United States

Major Cities Flows By/Through

Bismarck, N.D.; Pierre, S.D.; Omaha, Neb.; Kansas City, Mo.; St. Louis, Mo.

Where Name Comes From

Missouri Native American tribe

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David White