The winner of today's US presidential election will govern a nation of more than 330 million people, but the outcome will almost certainly depend on just a few tens of thousands of voters, a tiny fraction of the population in a handful of states.
That's because this year the situation is uncertain in only seven of the 50 states, while all the rest, according to polls, are overwhelmingly in favor of Democrats or Republicans.
Among those seven key states, the most populous Pennsylvania stands out as the one most likely to decide whether Democratic nominee Kamala Harris or Republican Donald Trump will be the next president.
The Reuters agency writes that this was also shown by the strategies of the candidates, who focused the vast majority of advertising funds and campaign events on these seven states that oscillate between the two political parties.
Why are elections not decided on the basis of national voting?
Unlike elections for other federal candidates and state offices, presidential elections are not based solely on the number of votes. Instead, a system known as the Electoral College is used, where the candidate who wins each state, as well as Washington DC, receives that state's electoral votes, which are largely based on population.
A candidate needs to win a majority of the 538 electoral votes - 270 - which is possible even if he loses at the level of the overall national vote, as happened to Trump when he won the 2016 election.
In the event of a 269-269 tie, the US House of Representatives selects the winner, with each state's delegation receiving one vote. Analysts say that scenario would likely favor former President Trump.
If all but swing states vote as expected, that would give Kamala Harris 226 electoral votes and Trump 219, with the remaining 93 votes up for grabs.
Which countries are uncertain?
It is not known what decision they will make for seven states, namely the trio of the so-called Rust Belt - Michigan, Pennsylvania and Wisconsin, and the quartet of the Sun Belt - Arizona, Georgia, Nevada and North Carolina.
Michigan, Pennsylvania and Wisconsin have served as the "blue wall" for Democrats for generations. However, Trump narrowly won all three states in 2016, resulting in his unexpected victory over Hillary Clinton.
Four years later, Joe Biden won the presidency by returning Michigan, Wisconsin and Pennsylvania to the Democrats, while surprisingly winning Georgia and Arizona, states that historically voted Republican.
This year's race is extremely tight. "The New York Times" announced on Sunday that, according to the monitoring of public opinion polls, there is a dead race in all the key states. Trump had an advantage of three percentage points in Arizona, while the other six states fluctuated within one point on average.
The race seems even more uncertain than in 2020, when a spillover of just 43.000 votes in three states — less than 1/3 of a percentage point of all voters in the country — from Biden to Trump was enough for the Republican to win again.
Why is Pennsylvania so important?
The simplest answer is that this state has 19 electoral votes, more than any other swing state.
Pennsylvania is widely seen as key to either Harris or Trump's chances of winning the White House and the most likely "breakthrough" state — one that would push the candidate over 269 electoral votes.
If Harris loses Pennsylvania, she would have to win either North Carolina or Georgia — two states that have voted Democratic just three times in the last four decades — to have any chance of victory.
On the other hand, if Trump loses Pennsylvania, he would have to win either Wisconsin or Michigan, which have voted Republican only once since the 1980s - for Trump eight years ago.
Both campaigns treated Pennsylvania as the most important state, with Harris and Trump spending more time there than in any other state. Campaigns and their allies spent $279,3 million on television advertising in Pennsylvania through Oct. 7, more than $75 million more than second-place Michigan, according to ad tracking firm AdImpact.
Why is one county in Nebraska getting so much attention?
Forty-eight states award electoral votes on a winner-take-all basis, but two states, Nebraska and Maine, award one electoral vote to the winner of each congressional district. In 2020, Biden won one in five votes in Nebraska, while Trump won one in four votes in Maine.
One electoral vote in Nebraska's 2nd Congressional District, based in Omaha, is considered up for grabs, though independent analysts predict Harris will win it. Both camps spent millions of dollars advertising in the Omaha market.
That one vote could be decisive. If Harris wins Michigan, Pennsylvania and Wisconsin, while Trump wins the other four key states, which is a very possible outcome, Nebraska's 2nd Congressional District will decide whether the election ends in a tie or Harris wins.
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