While Mrs Hillary Clinton has many plausible paths to victory, the options are fewer for Mr Donald Trump.
But though he enters the race as the underdog, a come-from-behind victory is certainly within the realms of possibility.
To give an indication of just the sort of steep hill he has to climb, consider the electoral college maths and the projections for each state.
A candidate needs 270 electoral college votes to win. Just based on solidly Democrat and solidly Republican states, Mrs Clinton starts the night with 268 votes in the bag, while Mr Trump starts with 191. A further 79 are up for grabs.
Mrs Clinton needs just two more to win. So if Mr Trump is to turn the tables, here is what he will need to do.
Option 1: Swing state clean sweep + the most competitive blue state
This path gives Mr Trump exactly the number of electoral college votes he needs and not a single one more.
It relies on him winning the most closely fought five states - Nevada, Ohio, Florida, North Carolina and Iowa - and then picking off New Hampshire and one electoral district in Maine.
Though Mrs Clinton has held a healthy lead in New Hampshire for most of the election campaign, the gap has closed significantly in the past week. In fact, three of the five most recent polls there put Mr Trump ahead. If he can then pick up one electoral vote from Maine, which does not operate on a winner-take-all model, he will have enough to become president.
It sounds like a big ask to win every major swing state but this path is the best chance for him to win.
Option 2: Three big prizes + blue state shockers
If he cannot win every swing state, he needs to at least secure the three biggest prizes in terms of electoral votes - Ohio, Florida and North Carolina. That - again assuming he picks up one of Maine's electoral votes - will leave him just 16 votes shy of 270.
He can find that by flipping one of the bigger states that are currently projected to go to the Democrats - Pennsylvania (20 votes), Illinois (20) or Michigan (16).
Alternatively, he will need to make up the 16 votes through some combination of smaller blue states where he has an outside chance - Wisconsin (10) and Colorado (nine) - with the remaining swing states Iowa (six) and Nevada (six).
Forecasters say most of those bigger blue states like Pennsylvania and Michigan are out of reach for him despite the high numbers of white working-class voters, so such a victory will be quite an upset.
Jeremy Au Yong
