And almost all states are winner take all, meaning whether a candidate wins a race by one vote or a million, they get the electoral votes.That sets up the possibility—particularly in a close race like this year—that the winner of the popular vote doesn’t win the presidency.

The quadrennial vote comes with a steep learning curve, as people and media outlets around the globe seek crash civics courses on the intricacies of the electoral college, a complex topic for U.S. voters that approaches the inscrutable for some abroad ...