The St. Francis Dam was a 200-foot high concrete gravity-arch dam built between 1924 and 1926 in St. Francisquito Canyon (near present-day Castaic and Santa Clarita). The dam collapsed on March 12, 1928 at two and a half minutes before midnight. The resulting flood killed more than 600 residents plus an unknown number of itinerant farm workers camped in San Francisquito Canyon, making it the 2nd greatest loss of life in California after the 1906 San Francisco earthquake. It is considered the worst American civil engineering failure in the 20th century.
