The Dam That Failed at Midnight — The Lesson That Built Hoover Dam

Just before midnight on March 12, 1928, the St. Francis Dam north of Los Angeles collapsed. A flood of more than twelve billion gallons ran 54 miles down San Francisquito Canyon and the Santa Clara River valley to the Pacific, killing at least 431 people (the exact toll has never been known). This is the story of William Mulholland and his dam, the night it failed, the telephone operators and motorcycle officers who raced to warn the valley, the investigations that followed, and how their lessons on geology, uplift and independent review shaped the building of Hoover Dam (1931–1936) by Frank Crowe, Six Companies and thousands of Depression-era workers. Every date and number in this video was checked against the sources listed below. CHAPTERS 0:00 Midnight, March 12, 1928 0:59 William Mulholland 2:35 Building the St. Francis Dam 4:28 The last day 6:36 The flood 8:46 The aftermath 9:47 The investigations 12:12 The lessons 13:24 The Boulder Canyon Project 15:47 Moving the Colorado River 17:41 Pouring the concrete 19:33 The workers 22:00 Dedication, 1935 23:36 Legacy today 24:58 Two dams SOURCES St. Francis Dam (Wikipedia): https://en.wikipedia.org/wiki/St._Fra... Hoover Dam (Wikipedia): https://en.wikipedia.org/wiki/Hoover_Dam USBR: Hoover Dam fatalities: https://www.usbr.gov/lc/hooverdam/his... USBR: Hoover Dam FAQ: https://www.usbr.gov/lc/hooverdam/faq... USBR: Concrete: https://www.usbr.gov/lc/hooverdam/his... USBR: High Scalers: https://www.usbr.gov/lc/hooverdam/his... USBR: Diversion Tunnels: https://www.usbr.gov/lc/hooverdam/His... California Division of Safety of Dams: https://water.ca.gov/Programs/All-Pro... SCVHistory.com: https://scvhistory.com/scvhistory/jb2... FDR's dedication address (American Presidency Project): https://www.presidency.ucsb.edu/docum... CREDITS Photos: Wikimedia Commons and the Library of Congress. Public domain U.S. Bureau of Reclamation photographs, Historic American Engineering Record (HAER) drawings and photographs, U.S. government works and pre-1930 press photographs, plus: St. Francis Dam ruins, crack (1928): Los Angeles Daily News, CC BY 4.0 Flood-twisted railroad track (1928): U.S. Geological Survey, CC BY 2.0 San Francisquito Reservoir map (2009): Kbh3rd, CC BY-SA 3.0 St. Francis Dam base remains (2009): Konrad Summers from Santa Clarita (Valencia) , California, USA, CC BY-SA 2.0 St. Francis Dam Disaster Memorial, Santa Paula (2012): Chris English, CC BY-SA 3.0 Los Angeles Aqueduct Cascades (1956): Los Angeles Times, CC BY 4.0 Colorado River basin map (2018): Shannon1, CC BY-SA 4.0 Hoover Dam dedication monument (2008): Ron Frazier from Bloomington IL, United States, CC BY 2.0 Hoover Dam intake towers (2012): Dietmar Rabich, CC BY-SA 4.0 Hoover Dam aerial view (2012): Shawn from Airdrie, Canada, CC BY-SA 2.0 Hoover Dam and low Lake Mead (2009): Raquel Baranow, CC BY-SA 3.0 St. Francis Dam and reservoir (1928): Imveracity, CC BY-SA 4.0 Powerhouse No. 2 after the flood (1928): SkyG702, CC BY-SA 4.0 Largest dam fragment downstream (1928): Imveracity, CC BY-SA 4.0 St. Francis Dam site and landslide (2009): Konrad Summers, CC BY-SA 2.0 Owens Valley aqueduct sabotage kit (1924): Los Angeles Times (UCLA Library), CC BY 4.0 Some black-and-white photos were colorized and enhanced for this video. Footage (public domain / Creative Commons): Boulder Dam: The Pictorial Record of Man's Conquest of the Colorado River (U.S. Department of the Interior, Bureau of Reclamation, 1930s; Prelinger Archives): public domain Boulder Dam, Part III (U.S. Bureau of Reclamation with Six Companies Inc. and The Babcock & Wilcox Co., 1930s; Internet Archive): public domain Reclamation in the Arid West (U.S. Department of the Interior, 1936; National Archives 11674): public domain The Story of Hoover Dam (U.S. Bureau of Reclamation, 1981; National Archives 37058): public domain Twenty Millionth Ford: Long Beach and Richmond Branches (1931; Ford Motor Company Collection, National Archives 200-FC-1376): public domain Santa Paula in 1929, Part 2 (1929; AV Geeks, Internet Archive): public domain [Home Movies: Grand Canyon, Boulder Dam, Las Vegas, Los Angeles] (1939; Prelinger Archives 0627): public domain Grand Canyon NP B-roll: Flat Water Boating and Reflections, Colorado River (National Park Service): public domain Lake Mead Recedes (NASA Scientific Visualization Studio / SSAI, Ross K. Walter; Landsat): public domain Hoover Dam Bypass Bridge construction time-lapse (Federal Highway Administration): CC BY 2.0 Music: original score created for Great American Works. #HooverDam #StFrancisDam #EngineeringHistory