A levee on the Mississippi River in Louisiana during the Great Flood of 1927. Hulton Archives/Getty Images hide caption

itoggle caption Hulton Archives/Getty Images

One of the two known photos of Robert Johnson. This portrait was taken by the Hooks Bros. Photography Company in Memphis, Tenn., circa 1935. Courtesy of the Delta Haze Corporation hide caption

itoggle caption Courtesy of the Delta Haze Corporation