I assume it's because Americans have too many elections on one day. Most other countries run local and state elections on separate days, and have far fewer elec

I assume it's because Americans have too many elections on one day. Most other countries run local and state elections on separate days, and have far fewer elected officers (usually just legislative). Most of those which do have elected executive officers hold those elections on another day (since the result is better for the president if they are elected a few weeks before the legislature).[1] I think only the US has elected judicial and law enforcement officers, which is actually scary to foreigners. If you have half the number of elections on two days, you can count all the ballots with half the number of people and still get a result by the end of the night. [1]: There's a few reasons for this. One is that a lot of people will say "okay, i'll give this person a chance" and even though they voted for the losing candidate, they decide to vote for the president's party in the legislature. Another is that if you ask people who they voted for, more people say the winner than actually voted for the winner. It seems there is some sort of problem of memory reliability here. Since more people believe they voted for the president than actually did, more people will happily support the presidents party than otherwise would have, had the election been synchronised.