Johnstown flood of 1936

The Johnstown flood of 1936, also collectively with other areas referred to as the Saint Patrick's Day Flood, was a devastating flood in Cambria County, and Johnstown, Pennsylvania proper, referred to as "Greater Johnstown".

The flood was preceded by heavy rains beginning March 9, 1936, which did not stop until March 22. The storms brought warmer weather with temperatures of 50 °F (10 °C) and was a cause of one stage of the flooding; the continuous rainfall was the second cause. The natural surface runoff of 1 to 3 inches (2.5 to 7.5 cm) was far surpassed by the deluge of from 10 to 30 inches (25 to 75 cm) of water in the region.

The flood came before pending flood control legislation was enacted or any significant flood control measures were implemented. The narrowness of the valleys and the encroachment of buildings on riverbanks contributed to the record flooding. By the time nightfall on March 17, one-third of the city was under 17 feet (5.2 m) of water. Twenty-five people lost their lives in the disaster, and damages estimated at $43 million made it the worst flood since the flood of 1889. The event is chronicled at the Johnstown Flood Museum.

After the flood, sweeping nationwide flood control laws were enacted and from 1938 to 1943 Johnstown saw many projects completed. These measures gave residents the feeling that the area was now "flood free", and it was touted as such until the flood of 1977.