How Long is The Missouri River?

© Howieson

Written by Janet F. Murray

Updated: October 12, 2022

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The Missouri River is almost as long as the Mississippi River and meanders for a total of 2,341 miles.


Missouri is the U.S.’s longest river and is the Mississippi River’s longest tributary. Additionally, it is the second-longest river in North America. As a result, the Missouri River holds a prominent place in the history of the U.S. Its vast expanse has been instrumental in forming many societies along its banks over the centuries and remains the country’s primary transportation, sustenance, and irrigation artery.

Where Does the Missouri River Begin?

The world’s 15th-longest river starts at the confluence of the Gallatin, Jefferson, and Madison Rivers. This area lies west of Bozeman, Montana, U.S., with the headwaters forming the Three Forks area in the Rocky Mountains, at an elevation of 4,045 feet.

The Missouri River meanders for a total of 2,341 miles. From its source in the Rocky Mountains, it flows through seven different states.

It is astounding that this mighty river travels more than 2,300 miles before reaching the Mississippi River. It finally joins the Mississippi in the city of St. Louis, forming the world’s fourth-longest river system. From there, it continues its path southward to the Gulf of Mexico.

Which States Does this River Travel Through?

The Missouri River meanders through seven states in the United States

© Howieson

Although it is the longest river in the U.S., the Missouri River is also a tributary of the Mississippi River. Before joining up with the Mississippi in St. Louis, it first takes a journey through seven states. These states are:

  • Montana
  • North Dakota
  • South Dakota
  • Nebraska
  • Iowa
  • Kansas
  • Missouri

The Missouri River initially takes an intricate journey via the Great Falls. Then, it flows in a northward and north-eastward direction through western Montana. From there, it arrives in North Dakota, winding in a southeasterly direction. Then, this mighty river journeys on a southward course into South Dakota.
At this point, the river flow makes up part of the:

  • South Dakota–Nebraska boundary
  • Nebraska–Iowa boundary
  • Nebraska–Missouri boundary
  • The northern section of the Kansas–Missouri boundary

Once the river reaches Kansas, it turns eastward across west-central Missouri. It then turns south-eastward towards Jefferson City. Eventually, the final leg takes on an eastward twist, where it meets the Mississippi River in St. Louis.

What is The Jefferson-Mississippi-Missouri River System?

An Autumn view of the Historic Alley Springs Mill in the Ozark National Scenic Riverways, Missouri, USA


Understanding the Missouri River’s correlation with the Jefferson-Mississippi-Missouri system is essential. These three rivers form the fourth largest river system in the world.

They may not be in the top five on their own, but together they form a unique, world-class water system. The significance of this river system has relevance far back into American history. The indigenous people of America used the river as a source of water and transportation. Missouri has also shaped many agricultural societies along the way.

The Jefferson-Mississippi-Missouri River System is North America’s most prominent inland waterway. It serves and stimulates the transportation and recreation industries along the way because its massive drainage basin covers an area of 1,245,000 square miles. This benefits 31 U.S. states and two Canadian provinces. The total length of the Jefferson-Mississippi-Missouri River System is 3,979 miles.

How Deep is This River?

Although the Missouri is not the deepest in the world, it is still impressive in its own right. The honorific title of the deepest river belongs to Africa’s Congo River. Its incredible depths of 720 feet reach where no light can penetrate.

As for the U.S., the Hudson claims the title of the deepest river, with a depth of up to 215 feet. The Missouri River follows in second place, at a maximum depth of 200 feet.

Although the Missouri River is currently more of a ‘Gentle Giant’ than the ‘Big Muddy,’ its nickname can certainly explain its lack of depth. So-called the infamous ‘Big Muddy’ gets its name from the sediment pumped into its system.

Recently, the presence of dams and channels has improved this situation. But, the vast quantity of sediment could be responsible for the elevated sandy banks in the river.

How Wide is the “Big Muddy”?

Missouri National Recreational River

Sediment deposits affect the width of the Missouri River

©Jacob Boomsma/

The width of a river is not a precise science. This condition is because its topography differs between areas of flow. In addition, many elements dictate the landscape. Yet, it is a widespread belief that the Missouri River was once approximately 10,000 feet wide. Recently, the width has decreased, and scientists now believe it to be about 700 feet wide.

These figures can change due to soil erosion and silting. Scientists also measure the flow of a river or discharge in cubic feet per second. The Missouri River’s flow can be as high as 900,000 cubic feet or as low as 4,000 cubic feet, with sediment causing these variations.

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About the Author

I'm a freelance writer with more than eight years of content creation experience. My content writing covers diverse genres, and I have a business degree. I am also the proud author of my memoir, My Sub-Lyme Life. This work details the effects of living with undiagnosed infections like rickettsia (like Lyme). By sharing this story, I wish to give others hope and courage in overcoming their life challenges. In my downtime, I value spending time with friends and family.

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