Trump vs Clinton: America chooses its 45th president

The great spectacle - part circus, part blood sport; a political drama that is both a marathon and a sprint - is about to begin.

Forty two million Americans have cast a ballot already in early-voting states. On Tuesday, about 100 million more will follow suit.

But let's not normalize this election.

This is like nothing we've ever seen before and it should be viewed as both an alarming aberration and a sign of the strains that a populist revolt has put on the very institutions of American democracy.

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If there is one emotion that we've witnessed on the campaign trail these last two years it is this: Frustration.

A vast number of Americans feel that the political and economic elite has ignored the interests of ordinary working people.

Donald Trump brilliantly tapped into this mood. It was the rocket fuel that propelled his implausible candidacy.

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Mrs Clinton never harnessed the frustration, but she has pitched herself as experienced and optimistic. And we should never underestimate that she too is a radical in her own way: A woman now without touching distance of breaking a line of forty-four consecutive men to occupy the Oval Office.

• Profile: Donald Trump

• Profile: Hillary Clinton

So Tuesday is a remarkable day whatever happens. We have a contest for the ages: A consummate insider against the ultimate maverick. An experienced operator against a political novice. A gender choice that is historic. One candidate who talks of building bridges, the others of constructing walls. Two candidates who will take America in very different directions.

So there may be a time to be disturbed and concerned, and to wonder how this great nation so full of talent and restless energy can produced two such flawed presidential candidates.

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But let's leave that to one side for another 24 hours. Right now, let's watch and admire the spectacle of a nation that is struggling with its role in the world making its anguished choice.

Amid the many imponderables of Election 2016 we can say this for sure: It is a choice that will impact us all.

• Watch Trump vs Clinton: The Result from 10.40pm on Tuesday, November 8, on ITV