It's a knife-edge election. But dig deep enough and there are enough clues to suggest a winner

In the state of Pennsylvania, which is likely to tip the balance of the election one side or the other, polling aggregator 538 shows an exact tie, with both candidates at 47.8 per cent.

But with polling places to open within hours, there are some solid indications the race will go towards Kamala Harris.

The biggest and best indicator is the gender gap.

A poll from Marist shows Harris leading among women by 15 points. Trump leads among men by four.

And current indications are women are turning out in slightly greater numbers than men.

She is also picking up slightly more Republican defectors than Trump is picking up Democrats.

Harris campaign manager David Plouffe has stated undecided voters are breaking to her “by double digits”.

He noted the remaining undecided voters are “looking more friendly” to her than Trump.

Posting a graphic indicating women are outvoting men in early ballots, Trump acolyte Elon Musk tweeted overnight: “Men must vote!”

What appears to have cost Trump badly is his rally in Madison Square Garden last week, in which a comedian described Puerto Rico as a “floating pile of garbage”.

The joke reverberated around the substantial Puerto Rican community on the US mainland.

With nearly half a million Puerto Ricans living in Pennsylvania, the remark may be enough to swing the election.

Meanwhile in Nevada, respected political journalist Jon Ralston has predicted a win of 0.3 per cent to Harris.

Ralston is well-regarded nationwide for his ability to forecast how elections will turn out in the state.

And in the past few weeks, Trump’s famous rallies have become more sparsely attended.

The former president has been struggling to fill venues as Harris’ crowd numbers are growing.

But an unenthusiastic voter’s ballot counts just as much as an enthusiastic one. This election will likely come down to which party can turn out the reluctant voters.

The Trump campaign is putting hope in the pre-election polls overestimating Democratic support.

In 2016 and 2020, polls showed both Hillary Clinton and Joe Biden winning comfortably.

But Clinton ended up losing narrowly, and it took days for Biden’s victory to be clear.

But polls in the 2022 midterm election heavily favoured Republicans.

It is reasonable to assume the polls at large will be off by a few points. But there’s little to show ahead of time which party with error will favour.

In any case, anyone who predicts tomorrow’s results with confidence is both brave and foolish.

The first ballots will start to be counted at 9am tomorrow AEDT.

You can follow the results in our live blog tomorrow.