Nine states have at least one uncalled House race, some of which are so close they are headed to a recount. Then there’s California. About half of the yet-to-be-decided House races are in the state, which has only counted about three-quarters of its votes statewide.

Here's what you need to know if you are a last-minute voter.

These differences in how states count — and how long it takes — exist because the Constitution sets out broad principles for electing a national government, but leaves the det