The world is waiting to find out who will be President of the United States - arguably the world’s most powerful person.
But what is at stake for the United Kingdom?
For decades, the UK and US have been each other’s military partners of choice.
The UK has not done any major military operations without its American partner this century.
The choices of the next president for the world’s most powerful military, and how it is used, will, in turn, affect the UK.
America’s military basing around the world offers an insight into its network of friends and allies – more than 220,000 of its troops are stationed across the globe.
Then there are the places it is fighting, either with boots on the ground, or via air strikes.
The UK is heavily involved in two of the biggest US operations – Donald Trump is bringing thousands of US troops home from Afghanistan and has claimed victory over the so-called Islamic State terror group in Iraq and Syria.
"We’ve beaten them and we’ve beaten them badly, we’ve taken back the land," Mr Trump said in a video message.
Speaking at a rally, Mr Biden said: "In fact, it turned out, Trump’s secret weapon to destroy the so-called caliphate was a continuation of a plan we put in place."
Joe Biden also says he would bring the "vast majority of troops home from Afghanistan".
That would put him on a similar page to the current president.
Karin von Hippel, Director-General, Royal United Services Institute, said: "It’s really interesting with Trump – he is reluctant to use force, he thought the war in Iraq was a mistake.
"Biden’s not trigger-happy either, Biden is the one who wanted to pull troops out of Afghanistan when Obama re-committed to another surge there."
However, he and Donald Trump have very different approaches to the strongest formal tie that binds the UK and US.
"Trump has taken a battering ram to the NATO alliance; he treats it like it’s some kind of American-run protection racket," Joe Biden said.
Mr Biden promises to restore America’s relationship with the alliance, but President Trump says he has pushed NATO into making itself stronger and less reliant on the US.
Mr Trump said: "You know, I got the NATO countries to put up an extra $130bn going to $420bn a year."
Fact-checkers point out those are totals, not annual amounts.
Trump’s former national security adviser John Bolton says: "I think it’s possible he could pull out of NATO entirely."
Erol Morkoc, Republicans Overseas, added: "Absolutely, Trump wants to stay in NATO.
"And Trump is a businessman, he comes in, everybody is 'no' until they’re 'yes' – that’s the phrase in business, right?"
NATO’s biggest concern right now is Russia.
Its troops are in Ukraine, fighting on the opposing side to America in Syria, and carrying out poisonings with the nerve agent Novichok.
Dr Julie Norman, a Senior Teaching Fellow in Politics and International Relations at University College London, said: "We’ve seen Trump being quite cosy with Putin, being quite forgiving of Russia’s transgressions, you know, kind of making excuses and whatnot.
"With Biden, I think we’d see much more of a traditional approach, we’d see much more of a pushback to what are seen as Russian aggression, Russian meddling."
Donald Trump did hit back at Moscow for breaching the 1980s INF Treaty that limits missiles which can hit Europe, by pulling out of it.
He also pulled out of the international deal with Iran which allowed it to keep researching nuclear technology, but for peaceful purposes – a deal Joe Biden helped to broker and would re-join.
Donald Trump prefers sanctions, even economic warfare.
Mr Trump said: "We have a different kind of a relationship, we have a very good relationship and there’s no war."
Mr Biden said: "He’s legitimised North Korea, he’s talked about his good buddy who’s a thug, a thug, and he talks about how we’re better off and they have much more capable missiles."
It is unclear how much of this is on the minds of Americans already casting their early ballots, amid a pandemic and fears for their livelihoods.
But it is on the minds of people in the rest of the world, even if they don't get a say.
What impact will the US election result have on American defence? Watch our video and read the full story here.
Cover image: US President Donald Trump and Democratic presidential candidate Joe Biden at the September 29 Presidential debate.