How Many Gallons of Water Flow from the Mississippi River Every Second?

Written by Cindy Rasmussen
Published: July 24, 2022
Image Credit melissamn/Shutterstock.com
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The Mississippi River starts as a small stream flowing slowly from Lake Itasca in Minnesota. As it flows down toward Louisiana it collects water from other rivers and tributaries along the way. By the time it empties into the Gulf of Mexico, you can imagine why they call it the “Mighty Mississippi”.  But how many gallons of water flow from the Mississippi River every second?

How long is the Mississippi River?

From the start to end the Mississippi River flows 2,350 miles.

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The Mississippi River is about 2,350 miles long. The Mississippi is one of the longest rivers in the world, when combined with the Missouri River it is often considered the 4th longest river in the world.

Where does the Mississippi River start?

lake itasca 2
The headwaters of the Mississippi start at Lake Itasca in Minnesota.

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The Mississippi River starts from a small lake in north-central Minnesota, Lake Itasca. Here you will find a lake full of walleye, bluegill, crappie and perch. The river is only 20-30 feet wide and tourists enjoy taking pictures of themselves walking across the Mississippi.

Where does the Mississippi River end?

The end of the river is in New Orleans, Louisiana where it empties into the Delta and the Gulf of Mexico. The fish that make their home in the river in New Orleans include catfish, largemouth bass, and redfish.

How fast is the Mississippi River?

The Mississippi River starts at around 1.2 miles per hour at the headwaters. It gains speed as it goes down the river to an average speed of 3 mph when it reaches the end. Along the way, the currents can be faster or slower depending on water levels and weather conditions. A raindrop that starts out at the headwaters would take around 3 months to flow down to the end.

How many gallons of water flow from the Mississippi River every second?

As you can imagine, the Mississippi River gets stronger and moves more water as it travels south toward its eventual end. Let’s look at how many gallons of water flows from the Mississippi at 5 different points along the river.

Lake Itasca, MN: 45 gallons per second

At the start of the Mississippi River, the water flows from Lake Itasca to form the beginning of the Mississippi where it then meanders north a bit before hooking south to Minneapolis/St. Paul. At Lake Itasca the flow from the river is 45 gallons per second. According to the National Park Service, this is the equivalent of having one semi-truck trailer full of water slowly releasing all of its water over a 10-minute period. The average surface speed of the water at the headwaters is around 1.2 mph, slower than the average walking speed of 2.5-4mph.

St. Anthony Falls, Minneapolis, MN: 81,000 gallons per second

St. Anthony Falls
You can see the water crashing down over St. Anthony Falls in Minneapolis.

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When the river reaches St. Anthony Falls it has picked up some speed and volume. The flow measured over St. Anthony Falls in Minneapolis is 81,000 gallons per second. Quite a bit more than the start! If you want to see what 81,000 gallons of water per second looks like (and sounds like) take a hike on the Stone Arch Bridge over to the Falls where you will be amazed at the sheer power of the flow!

You can also take a tour at the St, Anthony Falls Lock and Dam Visitor Center. The National Park Service explains that at the Falls, the equivalent of 3 full semi-trucks of water go over the falls, not in 10 minutes but in 1 second! What a change.

St. Louis, Missouri: 1,000,000 gallons per second

From Minneapolis, the river flows along the Wisconsin border, down the Iowa/Illinois border, along the Missouri/Illinois border to St. Louis, Missouri. Besides the distance it has traveled, gathering water along the way, this is where you add in the flow from the Missouri River. The Missouri River is actually longer than the Mississippi, so you can imagine how much added water flow it is capable of. That is why it should not surprise you to learn that the number of gallons of water that flow from the Mississippi River every second in St. Louis is 1,000,000 gallons! If you want to check the daily flow you can visit the National Water Information System which monitors the daily flow. The exact measurement for July 23, 2022 was 138,000 cubic feet per second which converts to 1,032,311 gallons per second!

Memphis, Tennessee: 2,400,000 gallons per second

2,400,000 gallons of water flow from the Mississippi River per second in Memphis, Tennessee.

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About 130 miles south of St. Louis the Mississippi River gets another major influx of water, this time from the east and the Ohio River. The Ohio River meets the Mississippi in Cario, Illinois, then it keeps heading south to Tennessee. The Mississippi River supplies water to an estimated 18 million people in more than 50 cities, including Memphis, Tennessee. When it reaches Memphis it has more than doubled its volume from St. Louis and flows at a rate of 2,400,000 gallons per second!

Gulf of Mexico: 4.5 million gallons per second

Just past New Orleans, the Mississippi River discharges at a flow of 4.5 million gallons per second!

Kevin Ruck/Shutterstock.com

 After leaving Memphis the Mississippi continues down along the border of Arkansas and Mississippi, then Mississippi and Louisiana. It flows through Baton Rouge and on to New Orleans. It empties into the Gulf of Mexico just past the port in New Orleans. By this point, about 2,350 miles later, the river is flowing at 4.5 million gallons per second (600,000 cubic feet per second). When you compare this to our semi-truck analogy it is the equivalent of 166 semi-trucks parked next to each other, each one completely full and opening the back to release all the water…in one second! Now that is a lot of water!

How does the water flow from the Mississippi River compare to other rivers in the world?

Compared to some of the major rivers in the world, the Mississippi is the 15th largest when it comes to the volume of water it discharges (please note that this measure can change over time). Here are a few other notable rivers:

  • Amazon: the Amazon River in South America discharges 55,211,956 gallons per second (7,380,765 cubic feet per second).
  • Nile: the Nile River in eastern Africa discharges 747,603 gallons per second (99,940 cubic feet per second).
  • Yangtze: the Yangtze River in discharges 8,228,571 gallons per second at its mouth (1,100,000 cubic feet per second).

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About the Author

I'm a Wildlife Conservation Author and Journalist, raising awareness and suggesting actions we can all do to help wildlife. As a former elementary school teacher I have a love for learning and teaching. My goal is to get kids fired-up about animals. Learning about the animals we share this earth with makes life better. When I am not writing I am living the good life with my husband and six kids (we are down to two that are still at home...and our giant labradoodle, Tango!).