Deadly History of Texas' Flash Flood Alley

There is no doubt that the Fourth of July flooding event in central Texas will go down as one of the deadliest floods to ever strike the Lone Star State. At least 130 fatalities have been confirmed in the flood that unfolded when the Guadalupe River surged over its banks after several inches of rain fell in a period of just a few hours.

Texas has seen more than its fair share of catastrophic floods. This is particularly true for the region where the recent tragedy struck, the part of Texas Hill Country known in meteorological circles as "Flash Flood Alley." In fact, data shows that this is the deadliest place for flooding throughout the entire U.S., based on reports from 2006 through 2020.

Here is a look back at some of the worst flooding disasters to roar through Texas.

The Great Galveston Hurricane - 1900

Well before the time when hurricanes were given names, what was then known as the Great Galveston Hurricane struck as an estimated Category 4 storm packing sustained winds of 145 mph. The storm came ashore in the port city of Galveston on September 8, 1900. In addition to the powerful winds, the hurricane unleashed a storm surge estimated at 15 feet.

The roaring storm surge destroyed thousands of structures in its path, bringing down about half of the city's buildings. Officials estimate that up to 12,000 died in the aftermath as the city was cut off from the rest of the state for days.

City officials built a 17-foot seawall to protect itself from further flooding disasters. The event is now distinguished as being the worst natural disaster in U.S. history, prompting the creation of better forecasting tools and improved response infrastructure.

San Antonio Floods - 1913

San Antonio was located at the heart of a torrential rainfall event in early December of 1913. The flooding was triggered after an exceptionally wet fall season during a classic El Niño pattern. Approximately 180 people died in San Antonio when the city received between 20 and 25 inches of rain in just 15 days. Rainfall of this magnitude quickly overwhelmed rivers, streams, and creeks.

Like the disaster in Galveston, local officials learned from the tragedy to make improvements to the state's infrastructure. The Brazos River and Valley Improvement Association was formed in 1915 in response to the flooding. The San Antonio floods also prompted the state legislature to construct the first Lake Waco Dam.

San Antonio and Central Texas Flood - 1921

San Antonio was the focal point of another devastating flooding event in September of 1921. This flooding came at the hands of a Category 1 hurricane that tracked to the north after hitting the southeastern corner of Texas. While the storm had weakened considerably before reaching the Alamo City, it still had enough moisture to send days of heavy rain across the region.

Officials estimate that 51 people died in San Antonio with over 200 lives lost in total across central Texas. There were at least 13 bridges that were destroyed in the event. Local leaders responded by building the Olmos Dam a few years later, engineered to provide a bypass channel for water flowing through the downtown area to mitigate flooding. The now famous River Walk was built around this channel, serving as the heart and soul of the city's tourism district.

Central Texas Flood - 1978

Central Texas was once again in the bullseye of a catastrophic flooding event when a tropical rainstorm moved far inland from the Gulf, setting up heavy bands of rain across Flash Flood Alley. What was once Tropical Storm Amelia moved through the area in July of 1978. The moisture associated with this tropical weather maker lingered for days over the part of Texas Hill Country located to the west of San Antonio and Austin.

Rainfall amounts of up to 48 inches fell over the course of just three days, distinguishing it as one of the highest rainfall totals in American history. The town of Albany picked up 29 inches of rain in 24 hours, putting about 80% of the community underwater. A total of 33 people died as a result of this storm with economic damages coming in at about $110 million in 1978 dollars.

Hurricane Harvey - 2017

More recently, Hurricane Harvey sent unprecedented rainfall across Texas and Louisiana. Over 40 inches of rain were recorded in four days, making it one of the nation's most prolific rain events. A top rainfall reading of 60.58 inches was notched in Nederland, Texas, located to the east of Houston.

According to estimates from the National Oceanic and Atmospheric Administration (NOAA), Harvey's estimated damages clocked in at $158.8 billion. Even in modern times with all of the advances in forecasting, Harvey was still responsible for 68 fatalities.

The silver lining is that climate experts and local officials have taken lessons from all of these disasters and used that knowledge to help communities better prepare for future flood events.

Weather changes fast — help your community stay prepared. Share this story with friends, family, or your group chat.