TODAY’S the day, one that will doubtless go down as a defining moment in US political history. American presidential elections have come and gone over the years, but few can have been more significant in recent times.

Will it be Joe Biden and his Democrats who will take the country into the next four years or will Americans choose Donald Trump and a Republican administration to govern them again for another term?

At the time of writing ,and if the majority of polls are correct, then it would appear Biden will be sworn in come January as the next occupant of the White House.

But as any Democrat supporter will tell you after what happened in 2016, it’s never done until it’s done. Back then, Hillary Clinton won the national popular vote but not enough within the US Electoral College to make her leader.

Despite trailing both in national polls and in those key battleground states where the largest number of Electoral College voters sit, a Trump loss is not yet a foregone conclusion.

Already more than 90 million Americans have made their choice, voting in unprecedented numbers through postal ballots. Who they have chosen will become clear over the coming day or so – or will it?

I raise that doubt because the bottom line in this election is that no-one quite knows when or how it will end. Already the spectre of Trump contesting the outcome is rearing its head again, with the president threatening legal challenges to prevent ballots from being counted after today’s vote.

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“We’re going to go in the night of, as soon as that election is over, we’re going in with our lawyers,” Trump vowed, speaking to reporters last Sunday about Pennsylvania even before all votes are counted.

The state is, of course, one of the key battleground ones on which both sides have concentrated their campaigning teams up until the last minute. Be it Pennsylvania or elsewhere Trump has repeatedly claimed, without evidence, that postal ballots are open to fraud, warning of “bedlam” if no clear winner emerges quickly.

And therein perhaps lies the biggest danger about this election, it’s capacity to further open up wounds that could prove immensely damaging to the fabric of American democracy and the country’s standing in the world.

There is, to put it simply, the real possibility of the tensions and acrimony that have been the hallmarks of this campaign spilling on to the streets.

Even before this election, America was plagued by months of protests and racial unrest. It would not take much to light the blue touch paper again and a bitterly contested election outcome would most likely be just that.

Over the past few days, a number of incidents have shown how potentially volatile the situation is. In New Jersey, Trump supporters blocked highways and in Texas harassed a Biden campaign team aboard a bus. In Georgia, meanwhile, a Democrat rally was cancelled over fears that it might draw “a large militia presence,” from a nearby Trump event.

It does nothing to ease the tension when the president then chooses to tweet a video message of the bus incident saying, “I love Texas,” or after the FBI says it’s investigating the incident he tweets again, saying: “In my opinion these patriots did nothing wrong.”

Those emboldened by such rash and irresponsible messages could well become far more dangerous in the days ahead should Trump lose and decide on an all-out challenge to the result. Short of a very decisive victory for either party, America will remain on a knife-edge if a decision over the final outcome takes days or even weeks.

AMERICANS will not be alone in holding their collective breath, of course. For across the world including here in Scotland, we will momentarily look up from our own domestic concerns to watch the drama unfold across the pond and what its implications for us mean. Make no mistake about it, the outcome of the US election matters for Scotland in a number of significant ways.

Writing recently on this very issue, the Edinburgh-based political scientist Anthony Salamone outlined how Scotland and the US already share close political, economic, social and cultural connections.

That the current political relationship between Edinburgh and the Trump administration might leave much to be desired goes without saying.

That a Biden presidency would change that dynamic considerably as indeed it would do with the UK Government is also a given. For the UK Government there are obvious challenges that a Biden win would present given Boris Johnson’s readiness to hitch the UK’s wagons to Trump policies.

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As Salamone rightly points out, were Scotland to become independent, the main initial challenge for the Scottish Government during that transition to statehood would be in reassuring Washington that Scotland would remain a “reliable partner”.

The implications of Brexit, future relations with the EU and Nato would all figure significantly in this process of mutual reassurance

Should there be a Trump win, then of course Scotland would likely find itself at odds with the US President over more than his business interests or a golf course. Be it global trade, the United Nations, Nato, climate treaties and environmental protections or the Iranian nuclear deal, what happens today in America impacts on these issues and many countries across the globe.

Scotland in this regard is no different. It’s precisely for these reasons that it matters who ends up sitting in that Oval Office chair these next four years.

Today, America decides not only its own domestic political future, but its role on the world stage. On every level the outcome of this election will reverberate. That collective holding of the breath begins right now.