Why We Might Not Know the Winner on Election Night

On Tuesday, voters across the country will head to the polls—and then will have to wait as the ballots are counted to determine the next President of the United States. But there’s a good chance Americans will go to sleep tomorrow night without knowing the winner.

If, as expected, the race between Vice President Kamala Harris and former President Donald Trump is close, experts say the delay in counting mail-in ballots means that there might not be a clear winner on election night. 

​​”The closer the election is, the less likely we will be able to know on election night,” says Andrew Hall, Professor of Political Economy at Stanford University. 

Counting mail-in ballots takes longer because the process involves additional layers of processing and verification that in some states can’t begin until Election Day. “There's a much more complicated process that election offices go through in terms of getting those ballots and confirming that they are from registered voters,” says Jen Leighley, Professor of Political Science at American University. The ballots themselves have to be unsealed, and verification sometimes involves matching up a signature or photo ID.

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In 2020, mail-in ballots made up 46% of the vote as voters turned to the option during the pandemic. President Joe Biden wasn’t officially declared the winner until Saturday, Nov. 7, more than three days after Election Day. There have been delays in statewide races, too: In Arizona, a battleground state in the 2024 contest, the vote count for the 2022 gubernatorial election went on for days after the election after the state received a last-minute flurry of mail-in ballots.

In seven battleground states, varying laws mean that some will see results come in faster than others. Michigan, Georgia, and North Carolina all have pre-processing laws that help speed up the counting process. In Michigan, election officials can begin processing and verifying mail ballots eight days before Election Day. North Carolina begins the process five weeks before Election Day. In Georgia, mail-in ballots are counted as soon as they are received. Results in those states could be called quickly–even as soon as Election Night.

Arizona and Nevada, however, could be among the last to provide a clear picture of the outcome, particularly if the race is close. Most voters in Arizona and Nevada vote by mail. More than 75% of Arizona voters vote by mail, and many will drop off their ballots in person on Election Day, creating a backlog. Nevada accepts mail ballots postmarked by then for up to four additional days. In other key states, including Pennsylvania and Wisconsin, processing doesn’t begin until Election Day, which can lead to delays in a tight race.

And, in roughly half of the states in the U.S., voters are able to “cure” their ballots in the case of minor errors, such as a missing signature or photo. In some cases, voters are able to cure their ballot a few days after Election Day, which can further drag out the count.

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As more voters turned to mail-in voting during the pandemic, the shift was visible as the results trickled in. “Democrats voted by mail at significantly higher rates than Republicans,” says Hall. “The early counts tended to favor the Republicans. And then as the hours and days went by and the mail ballots were being counted, you saw this big shift back towards the Democrats.” In 2020, Trump was quick to blame his loss on the delay from mail-in ballots, calling the system “corrupt.” (Courts found no significant instances of fraud in the 2020 election.)

Hall says that any delays might open the door for more post-election litigation, which could slow down results even further. “[There’s] a tail risk of a period of genuine uncertainty over who has won the election and who's going to get certified that we haven't really experienced before,” he says. 

So when might the election be called? The answer hinges, Hall says, on when the “most contested, most crucial battleground states finish counting.” And that, experts say, is not likely to happen on Nov. 5.