The 11 Worst Floods in U.S. History

Floods take more lives and cause more damage than any other weather-related disaster in the United States, including tornadoes and hurricanes. Floodwaters and debris can cause damage to bridges, roads, homes, and businesses. It can take out power, phone, and cable lines and contaminate drinking water. More importantly, floods cause the devastating loss of loved ones and animals. Here are the 11 worst floods in U.S. history. 

Johnstown Flood

The Johnstown flood in Pennsylvania occurred on May 31, 1889. After days of torrential rain, which released 14 million cubic meters of water, the South Fork Dam ruptured. The dam was 14 miles upstream of Johnstown, and its failure caused a flow rate equal to that of the Mississippi River. With a speed of 40 mph and a height of 60 feet, the muddy water filled with debris overtook several towns. The flood killed 2,209 people and caused $17 million in damages. 

Year: 1889

Location: Johnstown, Pennsylvania

Deaths: 2,209

Damages: $17 million

New Orleans Levee Failure

Hurricane Katrina made landfall in New Orleans and Mississippi, and on August 29, 2005, 50 levees and flood walls failed. The Army Corps of Engineers was faulted for its inadequate design and construction. Over 80% of New Orleans was flooded, destroying 100,000 homes and businesses. It’s still unknown how many people died from these levees failing, but it’s estimated to be around 600. $161 billion in damages resulted after the destruction of Hurricane Katrina and the levee failure. 

Year: 2005

Location: New Orleans, Louisiana

Deaths: 600

Damages: $161 billion

Great Mississippi Flood of 1927

Heavy rainfall in the summer of 1926 caused the Mississippi River to flood for several months in 1927. The flooding broke levees along the river in 145 places. More than 27,000 square miles of land were underwater, 700,00 people went homeless, 500 people died, and monetary damages exceeded $1 billion. More than 200,000 African Americans lost their homes and joined the Great Migration. Most of the people affected lived in Arkansas, Mississippi, and Louisiana. 

Year: 1927

Location: Arkansas, Mississippi, Louisiana

Deaths: 500

Damages: $1 billion

St. Francis Dam

The St. Francis concrete dam, located in Los Angeles County, CA, failed due to design flaws and defective soil. This dam was an integral part of the aqueduct system in the Sierra Pelona Mountains, about 40 miles northwest of downtown LA. The dam collapsed on March 12, 1928, triggering a massive flood that killed 431 people and caused around $7 million in damages. People still consider the dam collapse one of the worst engineering disasters of the 20th century.

Year: 1928

Location: Los Angeles, California

Deaths: 431

Damages: $7 million

Ohio River Flood of 1937

What could be worse than enduring the Great Depression and the Dust Bowl? How about a devastating flood that leaves you homeless with fewer family members. Water levels began to rise in the Ohio River at the beginning of January 1937. Heavy rains were falling nonstop, and the river’s banks were overflowing by mid-January. By the end of January, multiple cities were underwater, from Pittsburgh to Cairo, Illinois. Over almost a month, $500 million in damages accrued, one million people were homeless, and 385 people died.

Year: 1937

Location: Ohio, Indiana, Illinois, Kentucky, and West Virginia

Deaths: 385

Damages: $500 million

Great Dayton Flood

In March 1913, severe winter rain storms pounded the midwest. Within a few days, up to 11 inches of water fell into the Great Miami River Watershed. Soon after, the river and its streams began to overflow, the levees failed, and downtown Dayton, Ohio, was quickly flooded with 20 feet of muddy water. The amount of water that passed through the river channel during the storm was equal to the monthly flow from Niagara Falls. An estimated 360 died, and property damage soared by over $1 million. 

Year: 1913

Location: Dayton, Ohio

Deaths: 360

Damages: $1 million

Black Hills Flood of 1972

Fifteen inches of rain poured down over a small mountain range, known as the Black Hills, close to Rapid City, South Dakota. The Canyon Lake Dam, meant to hold back overflowing waterways, failed in the late evening of June 9, 1972. Severe flooding of residential flooding resulted in 238 deaths, 3,057 injuries, 1,335 homes destroyed, and over $160 million in damages. 

Year: 1972

Location: Rapid City, South Dakota

Deaths: 238

Damages: $160 million

Los Angeles Flood of 1938

Between February and March of 1938, two Pacific storms swept across the Los Angeles basin, generating a year’s worth of rainfall in a few days. Multiple rivers burst their banks and flooded the coastal plain, valleys, and the metro area. Around 115 people died and caused $78 million in damages, making it one of the costliest natural disasters in LA history. 

Year: 1938

Location: Los Angeles, California

Deaths: 115

Damages: $78 million

Great Flood of 1913, Columbus, Ohio

On March 24, 1913, over five inches of rain began to fall on Ohio. Several hours later, the major rivers were flooded, and soon after, first responders were standing in knee-high water. The state levee collapsed under the water’s pressure and poured into the lower elevation areas of Columbus (Franklinton), covering it in almost 17 feet of water. People climbed trees to escape the fast-moving flows, but some were so exhausted they fell into the water. Approximately 93 people died, and it’s unknown the number of damages accrued. 

Year: 1913

Location: Columbus, Ohio

Deaths: 93

Damages: Unknown

Johnstown Flood of 1977

On July 9, 1977, heavy showers of rain and flash floods poured down for 24 hours over the city of Johnstown, which had suffered a devastating flood in 1889. Six dams in the area failed, and water began pouring over the top and rushing into the city and nearby towns — millions of gallons of water flooded into the heavily populated area and created a depth of six feet. The estimated property damage was around $340 million, and 84 people lost their lives. 

Year: 1977

Location: Johnstown, Pennsylvania

Deaths: 84

Damages: $340 million

Austin Dam Failure

The Bayless Dam was known as “The dam that could not break.” After a week of rainstorms, the dam broke on September 30, 1911. The water abruptly flowed down the valley and crashed into the residents of Austin, Pennsylvania. More than 3,000 people were in town that day, and 78 perished under the rushing water and fast-moving debris. The destruction caused $10 million in property damage. 

Year: 1911

Location: Austin, Pennsylvania

Deaths: 78

Damages: $10 million

Summary of the 11 Worst Floods in U.S. History

Here’s a recap of the 11 most devastating floods ever in the United States:

What Have Been the Worst Floods in the World?

The four worst floods ever have all been in China:

• The 1887 Yellow River Flood, killing 930,000 to 2,000,000 people.
• The 1931 China Flood killing from 422,000 to 4,000,000 people.
• The 1935 Yangtze River Flood killing 145,000 people.
• The 1938 Yellow River Flood killing 400,000 to over 890,000 people.

The next three were in Europe:

• The Flood of 1099 in the Netherlands and England killed up to 100,000 people.
• The North Sea Flood and storm surge in 1212 killed an estimated 60,000 people.
• St. Lucia’s Flood and storm surge in 1287 affected the Netherlands and northern Germany, killing 50,000 to 80,000 people.