Mississippi River Flood of 1927 showing flooded areas and relief operation | |
| Meteorological history | |
|---|---|
| Duration | 1926–1929 |
| Flood | |
| Overall effects | |
| Fatalities | About 500 |
| Areas affected | ParticularlyArkansas,Louisiana, andMississippi – along withMissouri,Illinois,Kansas,Tennessee,Kentucky,Oklahoma, andTexas |
TheGreat Mississippi Flood of 1927 was the most destructiveriver flood in the history of the United States, with 27,000 square miles (70,000 km2) inundated in depths of up to 30 feet (9 m) over the course of several months in early 1927. The period cost of the damage has been estimated to be between $246 million and $1 billion, which ranges from $3.6–$14.5 billion in 2024 dollars.[1]
About 500 people died and over 630,000 people were directly affected; 94% of those affected lived inArkansas,Mississippi, andLouisiana, especially in theMississippi Delta region. There were 127 deaths inArkansas, making it one of the deadliest disasters ever recorded in the state.[2] More than 200,000 African Americans were displaced from their homes along theLower Mississippi River and had to live for lengthy periods in relief camps. As a result of this disruption, many joined theGreat Migration from theSouth to the industrial cities of theNorth and theMidwest; Black Americans preferred to move, rather than return to rural agricultural labor.[3]
To prevent future floods, the federal government built the world's longest system oflevees and flood-ways. Then-secretary of commerceHerbert Hoover's handling of the crisis gave him a positive nationwide reputation, helping pave the way to his election as U.S. president in1928. Political turmoil from the disaster at the state level aided theelection ofHuey Long as governor in Louisiana.


By the late nineteenth century, the United States was well aware of flooding potential along the Mississippi, which drained 40% of the nation's area. TheMississippi River Commission was established by the federal government in 1879, with the directive to deepen the river channel, improve navigation, prevent major flooding, and increase river-based commerce. This commission recommended raising extensivelevees along its channels to contain the flow, dismissing the advice of experts such asJames Eads, who had directed theSaint Louis Bridge project in the 1860s. These critics predicted that compressing a swollen river between walls would increase its destructive potential.[1]
Flooding began due to heavy rainfall in summer 1926 across the river's central basin. By September, the Mississippi's tributaries inKansas andIowa were swollen to maximum capacity. On Christmas Day of 1926,[4] theCumberland River atNashville, Tennessee, exceeded 56.2 ft (17.1 m), the second-highest recorded level (a destructive flood in 1793 had produced the record level – 58.5 ft (17.8 m)).[5]
Flooding peaked in theLower Mississippi River nearMound Landing, Mississippi, andArkansas City, Arkansas, and broke levees along the river in at least 145 places.[6] The water flooded more than 27,000 square miles (70,000 km2) of land, and left more than 700,000 people homeless. Approximately 500 people died as a result of flooding.[7] Monetary damages due to flooding reached approximately $1 billion, which was one-third of thefederal budget in 1927. If the event were to have occurred in 2023, the damages would total around $1.38 trillion to $1.48 trillion.
The flood affectedMissouri,Illinois,Kansas,Tennessee,Kentucky,Arkansas,Louisiana,Mississippi,Oklahoma, andTexas. Arkansas was hardest hit, with 14% of its territory covered by floodwaters extending from the Mississippi andArkansas deltas. By May 1927, theMississippi River belowMemphis, Tennessee, reached a width of 80 miles (130 km).[8] Without trees, grasses, deep roots, and wetlands, the denuded soil of the watershed could not do its ancient work of absorbing floodwater after seasons of intense precipitation.[9]

In an unrelated flood at the same time, on Good Friday (15 April 1927), 15 inches (380 mm) of rain fell inNew Orleans in 18 hours.[10] This far exceeded the City's rainwater pumping system, and up to 4 feet (1.2 m) of water flooded some parts of the city. This local rain-related flood was not connected to the Mississippi River flooding.
A group of influential bankers in New Orleans met to discuss how to guarantee the safety of the city, as they had already learned of the massive scale of flooding upriver.[10] On 29 April, they arranged to set off about 30 tons of dynamite on the levee atCaernarvon, Louisiana, releasing 250,000 cu ft/s (7,000 m3/s) of water. This was intended to prevent New Orleans from suffering serious damage, and it resulted in flooding much of the less densely populatedSt. Bernard Parish and all ofPlaquemines 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, released major amounts of flood waters, reducing the water that reached the city. The New Orleans businessmen did not compensate the losses of people in the downriver parishes.[11]
To address the disaster, Congress passed theMississippi Flood Control Act, which put greater stress on construction in theMississippi Delta levee camps despite warnings from theNAACP about harsh living conditions and mistreatment of black laborers within the camps.[12]

By August 1927, the flood subsided. Hundreds of thousands of people had been made homeless and displaced; properties, livestock and crops were destroyed. In terms of 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 theAmerican Red Cross through the efforts of local workers.[13]
African Americans, comprising 75% of the population in the Delta lowlands and supplying 95% of the agricultural labor force, were most affected by the flood. Historians estimate that 94% of the 637,000 people forced to relocate by the flooding lived in three states: Arkansas, Mississippi and Louisiana; and that 69% of the 325,146 who occupied the relief camps were African American.[14] In one location, over 13,000 evacuees nearGreenville, Mississippi, were gathered from area farms, and evacuated to the crest of the unbroken Greenville Levee. But many were stranded there for days without food or clean water.[12]
Following the Great Flood of 1927, multiple states needed money to rebuild their roads and bridges. Louisiana received $1,067,336 from the federal government for rebuilding,[15] but it had to institute a state gasoline tax to create a $30,000,000 fund to pay for new hard-surfaced highways.[16]
TheCorps of Engineers was charged with taming the Mississippi River. Under theFlood Control Act of 1928, the world's longest system of levees was built. Floodways that diverted excessive flow from the Mississippi River were constructed.[17] While the levees prevented some flooding, scientists have found that they changed the flow of the Mississippi River, with the unintended consequence of increasing flooding in succeeding decades. Channeling of waters has reduced the absorption of seasonal rains by the floodplains, increasing the speed of the current and preventing the deposit of new soils along the way. The levees did not prevent recurrences of significant flooding, especially a major flood in 1937. To better study and plan for future situations, Lt. Eugene Raybold proposed laying out a physical hydraulic model to simulate the basin's response to various rainfall scenarios. Land was procured at the SE edge ofClinton, Mississippi, and a 200-acre hydraulic model was constructed, matching to the river's flow fromBaton Rouge toOmaha, modeling the confluence points of its major tributaries across 16 states. The work was completed during 1942, with some labor provided byPOWs fromCamp Clinton.[18][19] The Corps used this model to accurately study river flows and mitigation strategies, but by 1970 it fell out of use. In the 1970s it was transferred to the city government of Jackson, and the Buddy Butts Park[20] was created around it.[21] It is presently little-known or recognized.[22][23]
The devastation of the flood and the strained racial relations resulted in many African Americans joining theGreat Migration from affected areas to northern and midwestern cities, a movement that had been underway sinceWorld War I. 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 and killed by a white police officer when he refused to unload a relief boat at gunpoint.[24][25] NearHelena, Arkansas,Owen Flemming was lynched after he killed a plantation overseer, who wanted to force him to rescue the plantation owner's mules.[26] 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, particularlyChicago; many thousands more followed in the following decades.[27][28]

Herbert Hoover enhanced his reputation by his achievements in directing flood relief operations asSecretary of Commerce under PresidentCalvin Coolidge. The next year Hoover easily won theRepublican 1928 nomination for President, and the general election that year. In upstate Louisiana, anger among yeomen farmers directed at the New Orleans elite for its damage of downriver parishes aidedHuey Long's election to the governorship in 1928.[29]: 408–409, 477, 487 Hoover was much lauded initially for his masterful handling of the refugee camps known as "tent cities".[30] These densely populated camps required basic necessities which were difficult to attain, such as water and sanitation facilities. Hoover used a combination of bureaucratic resources and grassroots forces to give the tent cities the opportunity to become self-sufficient. This method presented difficulties, as rural leaders were unprepared to manage the chaotic circumstances found in large camps. This led Hoover eventually to place the relief camps under government supervision.[30]
The refugee camps also dealt with extreme racial inequality, as supplies and means of evacuation after flooding were given strictly to white citizens, with blacks receiving only leftovers. African Americans also did not receive supplies without providing the name of their white employer or voucher from a white person. In order to fully exploit black labor, blacks were frequently forced to work against their will, and were not permitted to leave the camps.[31] Later reports about the poor treatment in camps led Hoover to make promises of change to the African-American community, which he broke. As a result, he lost the black vote in the North in his re-election campaign in 1932.[29]: 259–290 [note 1] Several reports on the terrible situation in the refugee camps, including one by the Colored Advisory Commission headed byRobert Russa Moton, were kept out of the media at Hoover's request, with the pledge of further reforms for blacks after the presidential election in 1928. His failure to deliver followed other disappointments by the Republican Party; Moton and other influential African Americans began to encourage black Americans to align instead with the nationalDemocrats.[29]: 415
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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.
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