Scene from the 1927 flood

The Great Mississippi Flood in 1927 was the most destructive flood in United States history.

In the Great Mississippi Flood of 1927 the Mississippi River broke out of its levee system in 145 places and flooded 27,000 square miles or about 16,570,627 acres (70 km²). The area was inundated up to a depth of 30 feet (10 m). The flood caused over $400 million in damages and killed 246 people in seven states.

The flood affected Arkansas, Illinois, Kentucky, Louisiana, Mississippi, and Tennessee with Arkansas being hardest hit with 13% of its territory covered by floodwaters.

The flood began when heavy rains pounded the central basin of the Mississippi in the summer of 1926. By September the Mississippi's tributaries in Kansas and Iowa were swollen to capacity. On New Year's day of 1927 the Cumberland River at Nashville topped levees at 56.2 feet (17 m).

By May of 1927 the Mississippi River below Memphis, Tennessee was a watery oval up to 60 miles wide (100 km).

The flood propelled Secretary of Commerce Herbert Hoover into the national spotlight and set the stage for his election to the Presidency.

As the flood approached New Orleans, Louisiana 30 tons of dynamite were set off on the levee at Caernarvon, Louisiana and sent 250,000 ft³/s (7,000 m³/s) of water pouring through. This prevented New Orleans from experiencing serious damage but destroyed much of the marsh below the city. As it turned out, the destruction of the Caernarvon levee was unnecessary; several major levee breaks well upstream of New Orleans, including one the day after the dynamiting, made it impossible for flood waters to seriously threaten the city.

By August 1927 the flood subsided. During the disaster 700,000 people were displaced, including 330,000 African-Americans who were moved to 154 relief camps. Many African-Americans were detained and forced to labor at gunpoint during flood relief efforts. The aftermath of the flood was one factor in the Great Migration of African-Americans to northern cities.

References

• Rising Tide: The Great Mississippi Flood of 1927 and How It Changed America by John M. Barry, ISBN 0684840022