It's not yet 8am on the East Coast but pictures are pouring in of voters queuing up to have their say.
Election staff in Philadelphia - a city in crucial swing state Pennsylvania - were snapped being sworn in before they could start processing votes.
Vermont was the first state to open its stations at 5am ET this morning - with these states following at 6.30am.
At 6.30am, North Carolina, Ohio and West Virginia stations opened their doors too.
Then at 7am ET the following states began to open the doors to some of their stations too:
In November 2000 George W Bush bagged an election victory over Al Gore with just a few hundred votes in Florida.
The disputed result ended up making it all the way to the Supreme Court – with an official win not declared until December 12, over a month later.
Some experts have speculated at whether the same thing could happen this time, if a recount row is sparked by very small margins.
Harris and Trump are incredibly close in the polls, with the Democrat nominee leading by a mere 0.7% as of Tuesday morning.