Why an election for 330 million-plus people may still come down to so few votes

A version of this story appears in CNN’s What Matters newsletter. To get it in your inbox, sign up for free here.

Anyone who pays any attention to US politics is bound to hear some version of this claim: The 2024 election, which will pick a president for a nation of more than 330 million people, will be decided by a small number of voters in a few key states.

There are concerns, particularly among Democrats, that President Joe Biden is losing support in these key states and they have pressured him to step aside for a different candidate.

But even an attempted assassination of former President Donald Trump and questions about Biden’s fitness to serve another four years might not interrupt the larger dynamic of the race.

“I still think that this is a race where we are not going to see the polls move outside a pretty narrow window,” Republican pollster Kristen Soltis Anderson said on CNN during coverage of the Republican National Convention.

“If you liked Donald Trump last week, you still like him this week. If you liked Joe Biden last week, you still like him this week,” she said.

With those perceptions set, consider just how small the margins were in the 2020 election, consider that the states Biden turned from red to blue to defeat then-President Trump were won by securing a tiny fraction of voters in those states.

In a 2024 rematch between the two, Trump will try to win those same states back from Biden, the Democrat aiming to win another term in the White House in November. The margins could be just as close.

But to say that a small number of voters “decide” the election is a major oversimplification of the American system and how it has evolved.

Here’s how things work:

There are 538 Electoral College votes split among the 50 states and the District of Columbia. Each state gets at least three votes, depending on the size of their congressional delegation.

The smallest states get three (they have two senators and one member of Congress). Washington, DC, also gets three. The most populous states get a lot more. California gets 54 electoral votes (it has two senators and 52 congressional districts). Texas has 40, Florida has 30, New York has 28 and so on.

The winner is the candidate who gets 270 or more electoral votes. If no candidate gets to 270 electoral votes, the House of Representatives picks the winner from among the candidates who got electoral votes.

A dozen states were decided by 5 percentage points or less in either the 2016 or 2020 presidential election. In CNN’s 2024 race ratings, Maine is the only one of these states rated as solidly in one party’s corner, but one congressional district within Maine is classified as a toss-up. The other 11 states are seen as competitive in the 2024 election. See the ratings here.

Viewed another way, we can expect that those states where the previous elections have been close to be the ones where the 2024 election will again be close. Polling backs up this presumption.

In real numbers, the close margins in those relatively few states equal a very small number of voters in a country of more than 330 million people, but they are necessary for either candidate to reach an Electoral College count of 270. Some of those states came down to tens of thousands of votes. Biden won for Democrats in five states in 2020 – Arizona, Georgia, Pennsylvania, Michigan and Wisconsin – where Hillary Clinton lost, often by very small margins, in 2016. Florida, on the other hand, which has been a battleground for years, went more toward Trump in 2020.

The campaigns will focus more attention on the fewer than one-third of all electoral votes they consider to be up for grabs or winnable by either party.

Another thing to consider is that the number of electoral votes was reallocated after the 2020 election due to the every-10-years census required by the Constitution. North Carolina, Colorado and Florida, potential battlegrounds, each gained an electoral vote. Texas, which Democrats have long hoped would become a battleground but which continues to tilt Republican despite shifting demographics, also gained two votes. Pennsylvania and Michigan are among the states that lost a vote.

That also means that the populations of these states are changing over time. A battleground in 2024 could look very different in the future. And states that seem safe for either party today could be battlegrounds in the future.

Two states, Maine and Nebraska, apportion some of their electoral votes by congressional district rather than giving all of them to the state winner. In 2020, for instance, Biden won a single vote in Nebraska and Trump won a single vote in Maine. These individual electoral votes could be incredibly important in the event of a tight election this year.

The end result is that, yes, the 2024 election could again come down to relatively few voters in relatively few states.

But questions remain over who those decisive voters are. Are they the voters who make most states reliably red or blue in most elections? Are they suburban women who were turned off by Trump in 2020, or are they people without a college degree who have moved toward the GOP? Are they older voters who have been trending toward Democrats or younger voters expressing an interest in Republicans? Are they more disinterested voters who only take part in the process every now and then, or is it a question of which party successfully motivates its stalwarts to turn out no matter what?

It will take all of the above for either candidate to win. However, because the margins in certain states could be so small, incremental shifts in the preference or turnout of any larger group of voters could be decisive.

For more CNN news and newsletters create an account at CNN.com