The Johnstown Flood

After days of heavy rain, the South Fork dam gave way and released some 14 million cubic metres of water down a narrow valley. The wave reached Johnstown in under an hour, travelling at about sixty kilometres an hour and carrying houses, trees and railway carriages with it.

Two thousand two hundred and nine people died, a third of them never identified. The dam had been poorly maintained by a private club whose members included Andrew Carnegie and Henry Clay Frick; no court ever held it liable.