Polls open for 2024 US Election Day as Kamala Harris, Donald ...

Washington, DC – Election Day is finally here.

Polls have opened for the 2024 United States election, a national vote that will decide not only the next president of the country but also the makeup of the House of Representatives and the Senate.

Tuesday caps a mad-dash stretch of campaigning that saw Democratic candidate Kamala Harris and her Republican challenger Donald Trump crisscrossing the country in hopes of shoring up voters.

For weeks, polls have shown a remarkably tight race, with no candidate having the edge going into Election Day.

Whatever the outcome of the vote, the result will define US politics and policy for the next four years. It will also be historic as voters will either elect the first female president in Harris or the first convicted felon in Trump.

In the final sprint of the race, both candidates have laid out vastly different visions for the country’s future. They have also staked out divergent positions on key issues like the economy, immigration, women’s rights and democracy.

Harris has pledged to “turn the page” on what she calls Trump’s divisive rhetoric. She has also positioned herself as a “new generation” leader who will boost the middle class, protect women’s rights and maintain the integrity of US institutions at home and abroad.

Nevertheless, she has faced regular protests over her support for Israel’s war in Gaza and Lebanon.

Trump, meanwhile, has promised a return to a US “golden age”. To do that, he has sketched a plan to lift economic regulations, project US strength abroad and crack down on migrants – a line of attack that regularly dips into racist tropes.

But while the candidates’ platforms have starkly contrasted in both substance and tone, they overlap on one lofty theme: that the outcome of this year’s vote is pivotal.

Trump has dubbed the 2024 race “the most important” one the country has ever seen, while Harris says it is the “most consequential” of voters’ lifetimes.

Both candidates spent the final 24 hours ahead of Election Day busily campaigning in key states.

“With your vote tomorrow, we can fix every single problem our country faces and lead America – indeed, the world – to new heights of glory,” said Trump as he delivered his closing pitch at the final rally of his campaign in the early hours of the morning in Grand Rapids, in the swing state of Michigan.

Harris said “the momentum is on our side” as she signed off in Philadelphia.

“We must finish strong,” the Democrat candidate declared. “Make no mistake, we will win.”

Election Day is the culmination of weeks of early voting in some locations. Several states began early voting – whether by mail or in person – as far back as September.

Nearly 81 million voters already cast their ballot before Election Day, according to the University of Florida’s Election Lab.

That is more than half of the 158.4 million (PDF) total votes cast in the 2020 presidential election – and a sign of record turnout this year for early voting in some parts of the country.

Election Day will ultimately reveal not just which candidate comes out on top, but the full extent of the changing demographics of the US electorate.

The first voting site technically opened right after Monday midnight Eastern time (05:00 GMT, Tuesday) in the tiny New Hampshire town of Dixville Notch. The next slate opened at 5am ET (10:00 GMT) in Vermont.

Other polling sites will open as morning breaks across the six time zones that cover the 50 US states.

Once the polls close in the evening, the results may take hours or days to be tabulated. States cannot begin reporting their vote counts until polls close.

Results will start to trickle in by about 6pm ET (23:00 GMT) when the first polls close in states like Indiana and Kentucky.

The last polls will close in the states farthest west, Alaska and Hawaii, around Tuesday midnight ET (05:00 GMT, Wednesday).

After that, the timing of the results will come down to individual states, as the US does not have a centralised election system. Each state is responsible for tallying its ballots. The tighter the margins, the longer that process may take.

All eyes will be on seven key states that are likely to decide the outcome: Arizona, Georgia, Michigan, Pennsylvania, Wisconsin, Nevada and North Carolina.

In the US, the presidential election is decided not by the popular vote but by a weighted system called the Electoral College.

Under the system, each state is worth a certain number of Electoral College votes, equal to the number of senators and representatives in Congress each state has.

For example, the swing state of North Carolina has 14 representatives in Congress based on its population size. Two senators represent every state, bringing the total number of Electoral College votes for North Carolina to 16.

The outcome of the presidential race in a given state determines which candidate receives that state’s Electoral College votes.

All but two states have a winner-takes-all system: if a candidate wins the state, even by a small margin, they get all its Electoral College votes.

There are 538 Electoral College votes in total, spread across the US. Whoever passes the threshold of 270 wins the race.

Since certain states consistently lean Republican or Democrat, Harris is likely to win 226 Electoral College votes easily, and Trump is expected to carry 219 without issue. Beyond that, Harris has 20 paths to victory and Trump 21.

Al Jazeera will rely on The Associated Press news agency to determine who has won each state and, eventually, the overall election. The AP does not issue projections. It declares the result of a race only once a winner emerges and no other outcome is possible.

This year’s vote will conclude an election season that repeatedly saw historic upheavals.

Donald Trump, 78, has become the central figure in the Republican Party and has led a movement that has sown doubt in the US election process.

Trump first entered the White House in 2016 after a surprise victory over Democrat Hillary Clinton. But he fell short in his re-election bid in 2020, when Joe Biden bested him at the ballot box.

The Republican leader, however, never conceded defeat and instead claimed that widespread voter fraud cost him the race, an unsubstantiated assertion.

Critics say since his 2020 defeat, Trump has never really stopped campaigning, laying the groundwork for his present-day bid. He officially announced he would seek re-election in 2022 at his Mar-a-Lago resort in Florida.

But his campaign has, at times, been overshadowed by historic court cases. Trump is the first president, past or present, to face criminal charges.

Four separate indictments have been issued against him: one for withholding classified documents, one for falsifying business records and two for efforts to overturn the 2020 election results.

In the business records case in New York, Trump was found guilty on 34 felony counts. But rather than dampen his re-election prospects, his legal troubles have largely energised his base, according to polls.

Trump has pleaded not guilty to all the charges against him and has called the indictments evidence of a coordinated “witch-hunt” designed to derail his presidential bid.

But he was not the only candidate facing historic hurdles as he raced for the White House.

His Democratic rival Harris was not even a candidate until about three months ago. Initially, in April 2023, President Biden announced plans to run for re-election.

He cruised through the Democratic primary season, running largely unopposed in the state-level contests. But concerns about the 81-year-old’s age and ability began to mount as he hit the campaign trail.

A special counsel report released in February, for instance, said Biden “did not remember, even within several years, when his son Beau died” – something the president later denied. And Biden made several high-profile gaffes, calling Egyptian President Abdel Fattah el-Sisi the “president of Mexico”.

The concerns over Biden crescendoed after a stumbling debate performance in June, where the president seemed to trail off mid-thought.

By July, Biden had abruptly dropped out of the race, and Democrats quickly coalesced around his vice president, Harris.

By early August, enough Democratic delegates had sided with Harris in a virtual vote for her to be named the party’s nominee for the presidency.

But it was an unorthodox process: never before had an incumbent president dropped out so late in a race, and never in recent history had a major party nominee bypassed the traditional primary process.

The election may still break new ground. In the charged political climate, fears of physical threats to polling sites have surged like never before.

And after four years of Trump claiming that the 2020 election had been stolen, observers have warned he and his allies could challenge the 2024 race if the results do not go his way.

That means the cloud of uncertainty that has hung over US politics for months may not dissipate anytime soon.