After Reconstruction, the Republican Party thought it would own the votes of African-Americans — forever. But in 1927, a deluge of rain turned the Mississippi River into “an angry dark ocean.” Levees burst. Homes, crops and towns were washed away. Hundreds died. Tens of thousands fled for high ground.

Commerce Secretary Herbert Hoover organized the national flood relief effort. His quick and decisive action earned the eternal gratitude of many Southern voters — but not all. Whites were rescued with alacrity. Black families were largely left to fend for themselves.