South Fork Dam, built in 1840, was located upstream from Johnstown, Pennsylvania; population of 30,000. The dam was a part of the local canal system and by 1889 it had fallen into neglect.
On May 31st 1889, the residents of Johnstown were unaware of the effects the previous night’s rainfall had had on the dam. It was noticed by engineers who rushed to alert the town, but could not as the telegraph lines were down.
At 3:10 p.m. the dam burst. A flood of water rushed into Johnstown, reaching speeds of up to 40 mph. The water crushed anything that got caught in it’s way, and dragged homes and train carriages with it. Though some tried to found safety in taller buildings, the whirlpools created would drag even them down. When debris collided with the bridge located downstream, a fire erupted and caused further devastation.
Over 2,200 people died in the Johnstown Flood, the largest loss of civilian life at the time. The American Red Cross orchestrated a relief effort in the flood’s aftermath, one of their first during peace time. The efforts were launched 5 days after the initial flood, and it would take 5 years to complete rebuilding. Johnstown later had two more floods in 1936 and 1977.
A lasting effect of the Johnstown Flood was legal shifts towards Strict Liability, holding defendants in cases like the South Fork Dam liable for damage caused by their use of land.