The worst-case scenario is this: Friendly sheriffs allow armed groups to intimidate voters at the polls on Election Day. Trump narrowly leads on Election Night, then mail-in ballots start to be counted and shift the race against him. Trump somehow signals to his base to take matters into their own hands, and they do. People might lash out against minorities, rival protest groups, or the symbols of both, such as synagogues.
Or armed people might attempt to take over election administration centers or recount centers to try to move the needle in their favor. In 2000, Republican operatives descended on an office at the Miami-Dade supervisor of elections, where canvassers were recounting ballots, in what became known as the “Brooks Brothers riot.” No one died, but people were punched and kicked.
Still, there are a number of reasons to think this election won’t get violent. In most countries, violence tends to take place before elections, not after. So if we’re not seeing widespread violence now, we might be in the clear.