An interesting hypothetical at Aeon: Which historical event would you undo?
My first thought was that John C. Calhoun was not born. But upon further reflection, it’s fairly obvious from a U.S. history perspective: the assassination of Abraham Lincoln. The difference between whatever Lincoln would have done from 1865-68 compared to Andrew Johnson would have been so massive as to have probably significantly changed U.S. history. At the very least, you don’t have to wait 2 years for meaningful Reconstruction to be imposed on the South. One wonders whether a reasonably aggressive crackdown on white resistance immediately after the war would have dampened it later. Maybe, maybe not. But I think that’s my choice.