Controlling the River

Seasonal flooding is a natural event for a river. When a river floods, it spills beyond its banks into nearby low-lying areas. 

- Elizabeth Armstrong Hall

When the flooding ends and the river recedes back to its channel, it leaves behind silt on the floodplain. Silt is a fine dirt that holds water. The cycle of flooding, depositing silt, and receding waters makes the soil around rivers particularly good for growing things.

But as people began living permanently in the low-lying plains around the Mississippi, flooding on the river became destructive. When the Mississippi floods today, millions of people are affected. And because the river's drainage system covers more than 40 percent of the United States, wet weather in one section of the country can cause serious floods many miles away.

For example, in December 1926, snowstorms blanketed Montana, South Dakota, and Minnesota. Then in March 1927, blizzards buried Wyoming, Colorado, and Nebraska and parts of Texas, Oklahoma, and Missouri. Farther south, it rained. That spring, melting snow fed into nearby rivers, which overflowed their banks. Most of that water eventually reached the Mississippi.

By the time the Mississippi River rolled through Arkansas, Mississippi, and Louisiana that year, it was so swollen that the levees crumbled under the immense weight of the water. The river spilled into the farmlands and towns of the Mississippi River Delta. It filled 27,000 square miles, the size of four New England states. More than 600,000 people lost their homes. An estimated 500 people lost their lives. It was the biggest flood on record to hit the Lower Mississippi.