The Mississippi River has been part of the lives of those who live along its banks for thousands of years. From helping farmers grow crops to supporting businesses to supplying households, it has deeply shaped American history and culture.
But it is not always easy to live near the country’s second-longest river. The Mississippi floods most years, especially in the spring when melting snow and heavy rain cause the water to rise. Worse, a study found that the probability of a 100-year flood occurring in the Mississippi River system has increased by 20% over the last 500 years.
Importance of the Mississippi River
The river stretches about 2,350 miles from Lake Itasca in Minnesota to the Gulf of Mexico. It flows through Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Arkansas, Tennessee, Louisiana, and Mississippi. As the fourth-largest watershed in the world, it drains a massive amount of water. The Mississippi River watershed covers an area of about 3.2 million square kilometers, which could engulf all or parts of 31 states and two Canadian provinces.
It is not only massive in size, though. The river has been a lifeline for many generations of Americans. The Mississippi River supported the lives of the Native Americans and early settlers and continues to sustain communities, wildlife, and industry today. It is a vital commercial waterway, moving millions of tons of freight annually, including farm produce, petroleum, and other raw materials.
The Mississippi River also plays a major environmental role. It is a key migration corridor for over 300 bird species and home to more than 250 species of fish.
Causes of Flooding
Flooding along the Mississippi River is a result of a mix of human actions and natural forces that have built up over time. Several key factors contribute to the increasing frequency and intensity of these floods, including the following:
- Weather-Related Factors
While climate change is not directly causing floods along the Mississippi River, it’s making heavy storms more likely. As global temperatures rise, the air holds more moisture, leading to more intense and frequent rainfall events. A study shows that intense rainfall events are occurring more frequently across the U.S.
However, other researchers found that natural factors, such as rainfall, alone don’t fully explain the increase in flood frequency and severity in the Mississippi River. Instead, they believe that the main driver of today’s major flood risk are human activities.
- River Engineering
One of the main reasons the Mississippi River keeps flooding is the amount of engineering that’s been done to control it. Over the years, the river has been straightened and lined with concrete mats along its banks. Levees have also been built to prevent floodwaters from overflowing into the floodplain.
However, while river engineering has brought many benefits, it also had some serious downsides. These changes have made the river more likely to flood in extreme ways. In fact, roughly 75% of the increase in major flood risk can be linked to these man-made modifications.
Samuel Munoz, geoscientist and assistant professor of marine and environmental sciences at Northeastern University shared: “It is this process of channelization that, in theory, increases the amount of water that passes through the channel and how fast that water goes during a flood.”
- Loss of Natural Floodplains
Floodplains are low-lying areas along rivers that naturally absorb and store extra water during heavy rains or floods. Unfortunately, many of the natural floodplains along the Mississippi River have disappeared. Over the past several decades, much of the area has been developed.
A study that looked at land use changes from 1941 to 2000 found that more than 10,000 square kilometers of floodplains in the Mississippi River Basin were lost due to agricultural expansion. These changes are significant because they reduce the land’s ability to absorb and slow down rising waters. With fewer natural buffers, floodwaters now have fewer places to go, which makes nearby communities more vulnerable when river levels rise.
Notable Mississippi River Floods
Floods along the Mississippi River have been some of the most destructive and costly natural disasters in the country. Over the years, several major floods have become historically significant, not just for their scale but also for the lasting impact they left behind.
The Great Mississippi Flood of 1927
Started by months of rainfall that began in the summer of 1926 and continued into the spring of the next year, the Great Mississippi Flood of 1927 was the most devastating in U.S. history. The Mississippi River swelled to an astonishing 80 miles wide near Vicksburg. Then the flood spread across Illinois, Missouri, Texas, Tennessee, Kansas, Oklahoma, Arkansas, Kentucky, Mississippi, Indiana, and Louisiana.
In the end, the disaster affected an area of 27,000 square miles and left more than 700,000 people homeless. The damage exceeded $5 billion and 246 lives were lost before waters finally receded in August 1927.
The flood prompted the Flood Control Act of 1928, which gave the federal government the lead role in managing the Mississippi River and launched the Mississippi River and Tributaries Project.
The Great Flood of 1993
Lasting from May through September, the Great Flood of 1993 affected nine states: North Dakota, Nebraska, Minnesota, Missouri, Iowa, Kansas, Wisconsin, South Dakota, and Illinois. On August 1, the Mississippi River reached its highest water level at 49.58 feet at St. Louis, Missouri.
This historic flood devastated over 20 million acres of land and forced around 54,000 people to evacuate. More than 50 lives were lost, roughly 50,000 homes were damaged or destroyed, and total damages were estimated at $15 to $20 billion.
Mississippi River Flood of 2011
Causing $2.8 billion in damage, the Mississippi River Flood of 2011 impacted seven states: Arkansas, Kentucky, Mississippi, Louisiana, Missouri, Illinois, and Tennessee. The flood affected more than 43,000 people, inundated over 21,000 homes and businesses, and submerged 1.2 million acres of agricultural land.
The Mississippi River Flood of 2011 tested the U.S. Army Corps of Engineers’ Mississippi River and Tributaries system like never before. Floodwaters pushed levees, reservoirs, and floodways to their limits. While the flood control infrastructure largely functioned as intended, the flood revealed significant weaknesses. Damage to levees included instability, seepage, and the appearance of sand boils.
Living with the Mississippi River
The Mississippi River is a vital force that supports countless communities, economies, and ecosystems along its course. However, managing its powerful and unpredictable nature remains a complex challenge. Changing weather patterns contribute to more intense rainfall events, but human modifications have significantly increased the river’s flood risks.
Living with the Mississippi River means learning to work with its power. By staying informed and advocating for policies that protect both people and the environment, everyone can play a part in reducing risks and preserving this flowing lifeline.