4 Major Tributaries of the Mississippi River

Written by Jennifer Gaeng
Updated: June 25, 2023
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The Mississippi River is 2.350 miles long and has more than 250 tributaries.


The Mississippi River is 2,350 miles long, stretching from Minnesota to Louisiana. It is the country’s second-longest river. Mississippi’s 250 tributaries drain one-third of the nation’s landmass. A tributary is a freshwater stream that feeds a larger one. The mainstem is the parent river. Confluence is where tributaries meet the mainstem.

Any river system contains tributaries, but the Mississippi River is notable for the number and significance of its tributaries, making it one of the most significant river systems in the world. Today, we’ll discuss four major Mississippi River tributaries. We’ll look at their length, how much water they flow into the Mississippi, and where their watersheds cross!

Infographic of 4 Major Tributaries of the Mississippi River
Mississippi’s 250 tributaries drain one-third of the landmass of the U.S.

1. Big Black River

Black River in Lesterville, Missouri

Big Black River is a main Mississippi tributary starting in Webster County.

©Scott Sanders/Shutterstock.com

The Big Black River is a major Mississippi tributary. It begins in Webster County at Eupora in north-central Mississippi. It then runs 330 miles (530 km) southwest, merging into the Mississippi River 25 miles (40 km) south of Vicksburg. The river contains a lot of agricultural runoff-caused suspended silt. Therefore, most of its tributaries are silted. These tributaries are muddy, with some being rapid and sandy. Its basin drains 3,400 square miles and is 50-650 feet above sea level. It is 160 miles long and 25 miles wide. Most of its tiny tributaries flow seasonally in the upper basin. The area is steep, with 56% forested.

2. Ohio River

The Ohio River sustains many cities and is a major tributary of the Mississippi River.

©ESB Professional/Shutterstock.com

The Ohio River is 981 miles (1,579 km) long. It flows southwest from western Pennsylvania to the Mississippi River in southern Illinois, dividing the Midwest and South. It’s the third-largest river in the US by discharge volume and the largest tributary of the north-south Mississippi River, which divides the east and west. It’s North America’s sixth-oldest river. Six states border the river, while 14 states drain into its basin. The basin covers numerous southeastern states through the Tennessee River. Three million people drink from it.

3. Illinois River

Illinois River is one of many tributaries of the Mississippi River.


The Illinois River is a 273-mile (439 km) tributary of the Mississippi. The Illinois River drains 28,756.6 square miles in central Illinois. The drainage basin includes parts of Wisconsin, Indiana, and southwestern Michigan. The Illinois River is formed by the Kankakee and Des Plaines rivers in Grundy County, about 10 miles (16 km) southwest of Joliet. Barges convey grain and oil along the waterway. In the summer and early fall, leisure boats cruising the Great Loop use it. The Illinois River is part of the Great Loop, a river route around Eastern North America.

4. Missouri River

Missouri National Recreational River

The Missouri River is the longest river in the United States.

©Jacob Boomsma/Shutterstock.com

The Missouri River is America’s longest river. It travels east and south for 2,341 miles (3,767 km) until entering the Mississippi River north of St. Louis, Missouri, where it originates in the Eastern Centennial Mountains of southwest Montana. An area of over 500,000 square miles is drained by the river, including sections of 10 U.S. states and two Canadian provinces.

Nominally a tributary, the Missouri River is substantially longer than the Mississippi above the confluence. It carries an equivalent volume of water when compared with the Mississippi. By itself, it is not the world’s longest river system, but when coupled with the lower Mississippi River, it becomes so.

NumberTributaryRiver LengthDrainage Basin
1Big Black River330 miles3,400 square miles
2Ohio River981 milesBasin covers numerous southeastern states through the Tennessee River
3Illinois River273 miles28,756.6 square miles; includes parts of Wisconsin, Indiana, and southwestern Michigan
4Missouri River2,341 milesOver 500,000 square miles, including sections of 10 U.S. states and two Canadian provinces

In Conclusion

The major tributaries of the Mississippi River are vital habitats that transport a variety of sediment, chemicals, organic matter, and water that sustain a wide range of organisms. Tributaries can introduce both essential ecological components and harmful toxins when they combine with the mainstem. Thus, when rivers are close to developed regions, pollution from their tributaries is magnified, making the water unhealthy for drinking and for habitats. Many types of waste are discharged into the waterways, including residential and industrial waste.

The government is also very important in conserving waterways since river usage and sewage must be regulated by them. The most crucial thing is to raise public awareness of river health and its importance. Rivers will only be cared for with our joint effort. In this critical time, we must unite to protect our rivers. Otherwise, we will not be able to leave a lovely world to future generations unless we act now.

The photo featured at the top of this post is © iStock.com/Willard

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About the Author

Jennifer Gaeng is a writer at A-Z-Animals focused on animals, lakes, and fishing. With over 15 years of collective experience in writing and researching, Jennifer has honed her skills in various niches, including nature, animals, family care, and self-care. Hailing from Missouri, Jennifer finds inspiration in spending quality time with her loved ones. Her creative spirit extends beyond her writing endeavors, as she finds joy in the art of drawing and immersing herself in the beauty of nature.

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