In 1927, a horrible flood debilitated an enormous swath of land flanking the Mississippi River, reaching from southern Missouri down through Louisiana and into the Delta, causing almost $125 million in damage. Thirteen years later, Life magazine commissioned the Regionalist artist John Steuart Curry to depict a scene in which then-Secretary of Commerce Herbert Hoover witnesses and oversees the government’s rescue efforts on the banks of the deluged Mississippi. The magazine reproduced the over five-feet-wide...