Over 500 days after both presidential candidates launched their campaigns, over $1.3bn in campaign spending later, and after 30 million voters have already cast ballots, tomorrow the presidential election will, finally, end. But how to make sense of the election night coverage, if you are staying up? Here’s how…

 The US presidential election system works like this:

  • Each state is worth a certain number of “Electoral College votes” – think of these as points.
  • States with bigger populations are worth more points – California is worth 55, Wyoming just 3.
  • In each state, whoever gets the most votes, regardless of whether it’s a majority of the vote in that state, gets ALL of the state’s “points”.*
  • To win, you need to get 270 Electoral College votes – if no one gets 270, the House of Representatives will elect the next president, meaning a Donald Trump win.**
  • Most states are safe for either Clinton or Trump, so campaigns concentrate on the key swing states which could vote for either party.
  • The most important swing states this year are Florida, Michigan, North Carolina, Ohio and Pennsylvania. These are effectively the Big 5 which will decide the election.

POSSIBLE OUTCOMES OF THE BIG 5 STATES

Number of the Big 5 states won by Clinton

Number of the Big 5 states won by Clinton

Outcome of Election

3 or more

Clinton win

2, one of which is Florida

Clinton win unless Trump can win Colorado, Nevada and New Hampshire

2, one of which is Pennsylvania but not Florida

Clinton win unless Trump can win Colorado plus one of Nevada or New Hampshire

2, neither of which is Pennsylvania or Florida

Clinton win unless Trump wins Colorado or both Nevada and New Hampshire

1, which is Florida

Trump win unless Clinton can win Colorado, Nevada and New Hampshire

1, which is not Florida

Trump win

0

Trump win

As for when we’ll know, Florida’s polls close at midnight UK time, with North Carolina and Ohio following at 00:30. Michigan and Pennsylvania becoming the final key states to close their polls at one in the morning, UK time – although Colorado at 2am and Nevada at 3am could be significant as well if it is close.

Most states will count quite quickly, especially those with a large proportion of early voters, such as Florida and North Carolina. This means, unless it is exceptionally close, we are likely to know the winner by 4am.

What to do if you can’t wait for each state’s results? Well, in each key state, there are some swing regions to look at which act as a leading indicator of how things are going. In Florida, the central belt of the state running roughly from Orlando to Tampa is the key swing region. In Michigan, the brilliantly named Kalamazoo County tends to back the winning candidate. In Ohio, Ottawa County in the north of the state is a good barometer, while in Pennsylvania, Northampton County in the south-east is a good indicator. Finally, North Carolina is a tricky one to call – the key will be Clinton’s margin of victory in the big city areas of Charlotte and Raleigh. All of these will act as a pretty reliable guide to who is ahead in each state, before the full state results are known.

*Technically, there are exceptions to this. In Maine and Nebraska, the winner of each congressional district within the state gets an Electoral Vote – meaning you can lose the state, but still pick up some Electoral College votes. In practice, there are so few Electoral Votes at stake in both states that this fact is not very likely to matter at all.

**This is only possible if someone other than Trump and Clinton wins a state, or if they tied on 269 each. Such a scenario is highly unlikely. A more plausible scenario is that the outcome of an individual state is so close as to be subject to a recount of votes.