Failure of St. Francis Dam

Date: March 12, 1928 • Location: Castaic, United States

The failure of the St. Francis Dam (pictured) northwest of Los Angeles resulted in a flood that killed 400 people.

The St. Francis Dam, or the San Francisquito Dam, was a concrete gravity-arch dam located in San Francisquito Canyon in northern Los Angeles County, California, United States, that was built between 1924 and 1926. The dam failed catastrophically in 1928, killing at least 431 people in the subsequent flood, in what is considered to have been one of the worst American civil engineering disasters of the 20th century and the third-greatest loss of life in California history.