Early indications are that the polls have been proved wrong in many cases, with several swing states showing strong support for Donald Trump.
Despite that, Joe Biden looks as though he may have gained Arizona, a state that has been Republican for many years.
The election is still too close to call, but there are some trends in voting patterns that have become apparent.
1. The industrial north will decide it
Ohio is the ultimate bellwether state which Trump secured in 2016 with his appeal to its sizeable group of non-college educated white voters. His focus on manufacturing and the problems caused by outsourcing made the difference in eastern Ohio which had long voted Democrat but swung sharply right.
It is a bellwether because it has mirrored the national result in every election since 1944, apart from 1960.
In 2020, Mr Trump increased his vote by at least 150,000 on the 2016 result.
The blue wall consists of states that for numerous recent elections have gone Democrat but, in 2016, the rust belt states within it (Pennsylvania, Michigan, Wisconsin) turned red.
If what has happened in Ohio - which is also a northern state with large industrial areas - happens across the blue wall industrial states of the north, then it could spell defeat for Joe Biden.
Sky correspondent Cordelia Lynch says there are signs that Donald Trump has improved his turnout in those states on 2016.
The data shows increased vote share for Mr Trump in almost all the bellwether states, as well as Ohio.
Lynch says this is because states like Ohio are trending whiter, righter and older.
2. Coronavirus may be key
Donald Trump's attitude to the pandemic has split America, with many of those concerned by the level of infection in the country shocked at his approach to controlling its spread.
But many in the US say he speaks for them, due to their reluctance to wear masks or to have their livelihoods affected by lockdowns.
The arguments have raged as the US has seen a fifth of all the cases recorded worldwide.
Experts have said these factors may have had an impact on the way people have voted in several of the battleground states.
Their comments could be borne out by the data, which shows in states where the, for example, masks have been made compulsory in public places, Donald Trump's vote share has held up or even increased.
Former Republican presidential adviser Lanhee Chen told Sky News that some in several Democrat led-states - which have seen tougher restrictions - particularly in the industrial north, could have voted for President Trump because they supported his approach.
He said: "The coronavirus lockdowns, those are a very divisive issue. For Trump, he clearly rode this issue in Michigan, and used it to his advantage."
Political scientist Ashley Koenig said: "We do know that COVID has become very much polarised. It was a bi-partisan or non-partisan issue when it first went through the United States and now it's become highly polarised.
"So now there becomes this pitting against of the economy versus health and we've already seen some of the numbers in the exit polls... and there could be this contentious debates between those who feel the economy needs to move on, because they are losing their livelihood, their paychecks, versus those who want to uphold the safety of society."
3. The Latino vote was decisive in some Sun Belt states
In Florida, 48% of Latinos backed Donald Trump, possibly tipping the balance in the incumbent's favour. Democrats on the ground say they believe it was the Latino vote that was key to the president's success in the state, which would have been critical if Joe Biden was to win.
Mr Trump was declared the winner in Florida after 96% of the votes were counted.
Data shows how many more Latinos backed Mr Trump in 2020 compared with 2016.
Bradley Jackson, a Democrat activist in Florida, told Sky News he could see the effect as he campaigned.
He said: "One of the main things I did see was down in Miami Dade county - which is a Democratic stronghold - that the Hispanic population, mainly Cuban and Venezuelan, which have had socialist governments for so long, have taken that message that the GOP [Republican Party] have put out, calling Joe Biden a socialist and used that to convince people that this agenda is what is happening."
Mr Jackson added: "A lot of them may have come out and voted and may have done worse than Hillary Clinton's lead, for Joe Biden this year."
The impact was perhaps even more pronounced in Texas, which Democrats had at one time hoped to win, but where some areas with a high Latino population showed much higher levels of support for Mr Trump in 2020 than they did in 2016.
4. 'Shy Trumpers' came out
Many commentators have said that the polls may have been wrong because of a phenomenon call the Shy Trumper - voters who did not tell pollsters they planned to vote Trump, and then did.
Mr Chen told Sky News: "Biden was winning by a much larger margin. Polls are a reflection of assumptions about who will turn out to vote and pollsters have to do their best to guess who is going to turn out on election day.
"Clearly what Trump has been able to do in these states is to create electorate that are more favourable to him. He's turning out voters that are going to support him and demotivating those who would oppose him."
A comparison of the average scores in the final polls, the day before the election, and the actual votes on the day, show that Mr Trump appeared to pick up far more votes than he was predicted to.
5. The college-educated drift
Despite an early belief that it was the growing Latino population in places like Arizona making the difference, the data suggests it is the rise in the number of people with better levels of education.
Trump's margin in Arizona in 2016 was the smallest since Republican Bob Dole's loss to President Bill Clinton and the result in Maricopa (which includes Phoenix) was one reason why.
In 2020, the county appears to have flipped, with the Democrats, as of around 10.50am UK time, ahead by nearly 6 percentage points.
Maricopa is the county that includes Phoenix, a city that has seen an influx in recent years of better-educated Americans, attracted to a growing economy and higher tech industries. 32% of inhabitants of the county now have degrees, the same as the US national average. It is home to 60% of Arizona's population.
If Joe Biden wins, it will come despite a rise in support for Donald Trump among Latino voters, which has gone up in a similar way to as it has in Florida.
A similar phenomenon to that seen in Arizona regarding education was also witnessed in Minnesota, which Joe Biden won in 2020, as Hillary Clinton had in 2016.
6. Increasing urban/rural split
In several of the swing states, early indications are that Joe Biden saw an increased vote share, compared to that of Hillary Clinton in 2016, among those living in urban areas.
Urban areas sometimes have higher proportions of college-educated voters and people from minorities - groups that tended to support Mrs Clinton previously - but Mr Biden saw more of them support him this time in states such as Georgia, Minnesota and North Carolina.
The exception was Michigan, the home of the US car industry, where support for the Democrats appeared to fall in more urban areas, which has a high black population but a lower level of college education.