I loved Ben H. Winters’s Underground Airlines. It’s about an alternate history where instead of the civil war, there’s a variant of the Crittenden Compromise. So there’s still slavery in a few states.
There was just one problem: a throwaway line about Carolina. That’s the state formed, in this alternate history, by the merger of North and South Carolina. This would never happen. The US political system gives more power to smaller states. What state would give up a senator (and maybe a representative) to join another? None. Ever. And this gets to the heart of why there was a Civil War in the first place.
In 1860, the (then chiefly southern) Democratic party had won three of the past six presidential elections. The slave states had between them about 40% of the Electoral College votes. They had about 45% of the Senate. But they only had about 1/3 of the population (and under 1/4 excluding slaves, who certainly weren’t going to fight for the South). The combination of the three-fifths compromise and the Electoral College led the South to dramatically overestimate their true strength. This, in my view, was a major cause of the Civil War. Nobody starts a war they don’t expect to win. But it’s very easy to fool yourself into thinking that you might win.
The way that democracy helps prevent civil wars, is that a faction that loses an election knows that it’s outnumbered. By screwing with this function, the Electoral College increases the odds of a civil war in this country. (So do weird ways of counting prisoners). Leaving aside the fundamental unjustness of it, this is the true reason we ought to get rid of it.
Side note: The fourteenth amendment made the Electoral College unconstitutional at least at the current population numbers, but somehow no court has noticed this yet. Reynolds v. Sims found a state-level Electoral-College-like system unconstitutional. But there’s no reason that the logic of the case doesn’t apply to the federal system as well. The Senate too, of course.
All this is to say that you should read Underground Airlines, but ignore the Carolinas bit. It doesn’t affect the story at all.