The Johnstown Flood kills more than 2,200 in Pennsylvania

On May 31, 1889, after days of heavy rain, the South Fork Dam failed about 14 miles upstream of Johnstown, Pennsylvania. The earthen dam—poorly maintained and altered to serve a private mountain resort—gave way and released some 20 million tons of water into the valley below.

The flood reached Johnstown in the afternoon, traveling at roughly 40 miles per hour and scouring away homes, mills and railroad cars. It killed 2,209 people; around 900 of the bodies were never identified. It remains one of the deadliest dam failures in U.S. history.

One of the American Red Cross’s first major relief efforts followed, with Clara Barton arriving days later.

The disaster became a national lesson in engineering responsibility, fueling debate over the duty owed by those who build and maintain dams to the communities living downstream.