Great Mississippi Flood of 1927
The Great Mississippi Flood of 1927 was the most destructive river flood in the history of the United States, with 27,000 square miles inundated up to a depth of 30 feet. To prevent future floods, the government built the world's longest system of levees and floodways. Many African-Americans displaced from their homes along the Lower Mississippi River started a large migration North to the industrial cities.
The flood began with extremely heavy rains in the central basin of the Mississippi in the summer of 1926. By September, the Mississippi's tributaries in Kansas and Iowa were swollen to capacity. On Christmas Day of 1926, the Cumberland River at Nashville exceeded 56.2 feet (17 m), a level that remains a record to this day, higher than the devastating 2010 floods.
Flooding overtopped the levees, causing Mounds Landing to break with more than double the water volume of Niagara Falls. The Mississippi River broke out of its levee system in 145 places and flooded 27,000 square miles (70,000 km2). This water flooded an area 80 km (50 mi) wide and more than 160 km (99 mi) long. The area was inundated up to a depth of 30 feet (10 m). The flood caused over $400 million in damages and killed 246 people in seven states.
The flood affected Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri, Tennessee, Texas, Oklahoma and Kansas. Arkansas was hardest hit, with 14% of its territory covered by floodwaters. By May 1927, the Mississippi River below Memphis, Tennessee, reached a width of 60 miles (97 km).
Attempts at relief
On April 15, 1927, 15 inches (380 mm) of rain fell in New Orleans in 18 hours. More than 4 feet (1.2 m) of water covered parts of the city, and influential bankers in town met about how to guarantee the safety of the city, with the scale of flooding upriver already known. A few weeks later, about 30 tons of dynamite were set off on the levee at Caernarvon, Louisiana, and sent 250,000 ft³/s (7,000 m³/s) of water pouring through. This was intended to prevent New Orleans from experiencing serious damage but flooded much of St. Bernard Parish and all of Plaquemines Parish's east bank. As it turned out, the destruction of the Caernarvon levee was unnecessary; several major levee breaks well upstream of New Orleans, including one the day after the demolitions, made it impossible for flood waters to seriously threaten the city.
Abatement and assessment
By August 1927, the flood subsided.
In population affected, in territory flooded, in property loss and crop destruction, the flood's figures were "staggering". Great loss of life was averted by relief efforts, largely by the work of the American Red Cross. African Americans, comprising 75% of the population in the delta lowlands and supplying 95% of the agricultural labor force, were accordingly most affected. It has been estimated that out of the 637,000 people forced to relocate by the water, 94% lived in three states, Arkansas, Mississippi and Louisiana; and that 69% of the 325,146 who occupied the relief camps were African American. In one noted location, over 13,000 evacuees near Greenville, Mississippi, were gathered from area farms, evacuated to the crest of the unbroken Greenville Levee and stranded there for days without food or clean water, while boats arrived to evacuate white women and children. The Greenville Levee was eight feet wide and approximately five miles long.
Following the Great Flood of 1927, the Army Corps of Engineers was again charged with taming the Mississippi River. Under the Flood Control Act of 1928, the world's longest system of levees was built. Floodways that diverted excessive flow from the Mississippi River were constructed. States also needed money to rebuild existing roads and bridges. Louisiana, despite receiving $1,067,336.40 from the federal government for rebuilding,  also had to institute a state gasoline tax to create a $30,000,000 fund to pay for new hard-surfaced highways. 
The aftermath of the flood was one factor in accelerating the Great Migration of African Americans to northern cities. The flood waters began to recede in June 1927, but interracial relations continued to be strained. Hostilities had erupted between the races; a black man was shot by a white police officer when he refused to be conscripted to unload a relief boat. As a result of displacements lasting up to six months, tens of thousands of local African Americans moved to the big cities of the North, particularly Chicago; many thousands more followed in the following decades.
The flood further enhanced the reputation of Herbert Hoover, who was in charge of flood relief operations as Secretary of Commerce under President Calvin Coolidge. Hoover would later easily win the Republican nomination for President, and the general election, in 1928. In upstate Louisiana, anger directed at the New Orleans elite aided Huey Long's election to the governorship in 1928.:408–409, 477, 487 Hoover was much lauded for his masterful handling of the refugee camps, but later concerns over the treatment of blacks in those camps caused him to make promises to the African-American community that he later broke, losing the black vote in his re-election campaign in 1932.:259–290 Several reports on the terrible situation in the refugee camps, including one by the Colored Advisory Commission by Robert Russa Moton, were kept out of the media at Hoover's request, with the pledge of further reforms for blacks after the presidential election. When he failed to deliver, Moton and other influential African Americans helped to shift the allegiance of black Americans from the Republican party to the Democrats.:415
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- "Man vs. Nature: The Great Mississippi Flood of 1927". News.nationalgeographic.com. 2001-05-01. Retrieved 2014-03-22.
- Hornbeck, Richard; Naidu, Suresh (2014). "When the Levee Breaks: Black Migration and Economic Development in the American South†". American Economic Review 104 (3): 963–990. doi:10.1257/aer.104.3.963. ISSN 0002-8282.
- Evans, David (2007). "Bessie Smith's 'Back-Water Blues': The story behind the song". Popular Music 26: 97. doi:10.1017/S0261143007001158.
- Science Question of the Week - natural disasters, floods - April 05, 2002
- "American Experience | New Orleans | People & Events". PBS. 1927-04-15. Retrieved 2014-03-22.
- "The Final Report of the Colored Advisory Commission Appointed to Cooperate with The American National Red Cross and the President's Committee on Relief Work in the Mississippi Valley Flood Disaster of 1927". PBS. Retrieved 2010-07-16.
- "Timeline 1927 - 1929 (April 25)". PBS. Retrieved 2010-07-15.
The planters, in particular, oppose Will [Percy]'s plan [to evacuate blacks], fearing that if the African American refugees leave, they will never return, and there will be no labor to work the crops.
- William Alexander Percy (2006) . Lanterns on the Levee: Recollections of a Planter's Son. Reprint. Louisiana State University Press. pp. 257–258, 266. ISBN 978-0-8071-0072-1.
- "After the Flood of 1927". Houghton Mifflin. Retrieved 2010-07-15.
- "First check from Federal government for rebuilding after the flood of 1927" in Mississippi River Flood of 1927 Album (Mss. 4373), Louisiana and Lower Mississippi Valley Collections, LSU Libraries, Baton Rouge, Louisiana, USA. <http://cdm16313.contentdm.oclc.org/cdm/singleitem/collection/LSU_MRF/id/430/rec/57> (accessed 2 February 2015)
- "First gallon taxed gas sold to A. of C. officials…" in Mississippi River Flood of 1927 Album (Mss. 4373), Louisiana and Lower Mississippi Valley Collections, LSU Libraries, Baton Rouge, Louisiana, USA. <http://cdm16313.contentdm.oclc.org/cdm/singleitem/collection/LSU_MRF/id/553/rec/58> (accessed 2 February 2015)
- "One Man's Experience". PBS. Retrieved 2010-07-15.
The police were sent into the Negro section to comb from the idlers the required number of workers. Within two hours, the worst had happened: a Negro refused to come with the officer, and the officer killed him.
- "Voices from the Flood". PBS. Retrieved 2010-07-15.
After the flood, the Delta would never be the same. With their meager crops destroyed, and feeling deeply mistrustful of white Delta landlords after their poor treatment as refugees, thousands of African Americans left the area. Many headed north to seek their fortunes in Chicago.
- Barry, John M. (1998-04-02). Rising Tide: The Great Mississippi Flood of 1927 and How It Changed America. ISBN 0-684-84002-2.
- The Great Flood - Rotten Tomatoes
- The Great Flood (2012) - IMDb
- Barry, John M. (1997). Rising Tide: The Great Mississippi Flood of 1927 and How It Changed America. New York: Simon & Schuster. ISBN 0-684-84002-2.
- Daniel, Pete (1977). Deep'n As It Come: The 1927 Mississippi River Flood. New York: Oxford University Press. ISBN 0-19-502122-3.
- Payne, John Barton (1929). The Mississippi Valley Flood Disaster of 1927. Official Report of the Relief Operations. Washington, DC: American National Red Cross. OCLC 1610750.
- RMS Special Report (2007). The 1927 Great Mississippi Flood: 80-Year Retrospective (PDF). San Francisco: Risk Management Solutions. Retrieved 2014-12-06.[dead link]
- Sevier, Richard P. (2003). Madison Parish (Images of America). Charleston, SC: Arcadia. ISBN 0-7385-1510-8. Contains over 200 pictures of the flood as it affected the Tensas Basin in eastern Louisiana. Website with selected photographs from the book.
- Eldredge, Charles C. (2007). John Steuart Curry's Hoover and the Flood: Painting Modern History. Chapel Hill: University of North Carolina Press. ISBN 978-0-8078-3087-1.
|Wikimedia Commons has media related to Great Mississippi Flood of 1927.|
- A film clip of the Mississippi River Flood of 1927 is available for free download at the Internet Archive - Short silent film of the flood aftermath and relief efforts for the refugees. Produced by the US Army Signal Corps.
- Disaster Response and Appointment of a Recovery Czar: The Executive Branch's Response to the Flood of 1927 - Well-referenced CRS report.
- 1927 Flood Photograph Collection Historic images of the flood from the Mississippi Department of Archives and History
- Delta Geography Information about how the Flood of 1927 currently influences the life of people that live in the Delta
- PBS American Experience: Fatal Flood
- U.S. Army Engineers periodical "ESPRIT", March, 2002 - Lead article relying heavily on John M. Barry's book; includes some photographs.
- The Final Report of the Colored Advisory Commission Text of the report provided by "The American Experience"
- Historic video footage of 1927 Mississippi Flood and US Coast Guard rendering aid to flood victims
- Youtube video from the U.S. Army Corps of Engineers, Vicksburg District
- Mississippi River Flood of 1927 Album (Mss. 4373), Louisiana and Lower Mississippi Valley Collections, LSU Libraries, Baton Rouge, Louisiana, USA.<http://cdm16313.contentdm.oclc.org/cdm/landingpage/collection/LSU_MRF>