Post Civil War Apartheid in the U.S.

"Within three years of the Civil War's end, 'black voter registration ranged from 85 to 94 percent in the deep South, and almost one million freedmen were voting throughout the region.... By 1944, in the states of the old Confederacy, only 5 percent of age-eligible African Americans were registered to vote.'"
The Dixiecrat Dilemma in Ezra Klein's Why We're Polarized