Four years ago, during the COVID-19 pandemic, Americans had to wait days to find out the results of the presidential race. For the first time in decades, voters woke up on Wednesday morning still in limbo, unsure which way the country would turn. Now, with just days until the 2024 election, it’s on many minds — will that happen again?

Whether the election outcome is known on election night or a few days later will be determined by the combination of two things: how close the margin is and what the rules are for opening, processing and counting mail and early ballots in the key swing states.

The biggest factor in the 2020 delay was the dramatic increase in mail voting, as people tried to protect themselves and their communities from illness. But the increase — 65 million mail ballots were cast — ran up against laws in certain states that restricted, and delayed, when those ballots could be opened, processed and counted. It was obvious from the outset of the pandemic that, absent a landslide win, the winner of the 2020 presidential election would not be known on election night.

This was, and is still, totally normal. Election results have never actually been finalized on election night. But the public is accustomed to television (and now online) news sources projecting winners based on incomplete results on election night, leading to the perception that the results are conclusive.

While the official 2020 result remained in limbo, it was possible to predict which way the election would tilt based on partisan voting behaviors. Since Democrats took pandemic precautions more seriously and then-President Donald Trump spent months discouraging and demonizing mail voting, the outstanding ballots were known to tilt heavily in favor of Joe Biden. This dynamic created a “red mirage” on election night, where the in-person votes cast and counted on Election Day quickly skewed heavily in favor of Trump, while the mail ballots, which were counted later, would cause a “blue shift” in the vote total in favor of Biden.

In predictable fashion, Trump exploited this situation in 2020 with a torrent of lies. He declared at 2 a.m. after election night that “a fraud on the American public” had taken place by election workers counting the pro-Biden mail ballots after counting the more pro-Trump in-person votes.

“Frankly, we did win this election,” he added. It was the first step in what would become the Big Lie of his attempt to deny, and overturn, the election. He first sought to block the counting of the mail ballots and, when that failed, to prevent states he lost from being counted in the Electoral College vote, which culminated in the attack on the Capitol he fomented on Jan. 6, 2021.

Today, those same dynamics remain in effect in many of the key swing states, although there have been some changes.

The biggest change is obvious: Far fewer voters in key states are casting mail ballots than in 2020. This could make reporting results quicker in some of these states. On the other hand, some states — specifically Republicans in those states — continue to disallow mail ballots to be processed and counted prior to Election Day. That makes the count slower and helps produce the conditions for the red mirage and blue shift.

This is how and when (eastern time) polls in each of the seven swing states close — and what factors will determine when we learn which ones ultimately tilted for either Vice President Kamala Harris or Trump.

7 p.m.: Georgia

The swing state with the earliest poll closing time was also one of the last to be decided in 2020. Georgia officials declared Biden the winner of the state on Nov. 19 — two weeks after the election. After multiple audits, state officials determined Biden beat Trump by just 11,779 votes.

The long wait for a final result back then was driven by the pandemic-induced deluge of mail ballots and the razor-thin margin.

Georgians cast a record 1.3 million ballots by mail in 2020. So far this year, that number is way down, with slightly more than 300,000 mail ballots requested. These ballots can be processed prior to Election Day and counted beginning at 7 a.m. on Election Day. This could speed up the reporting and projection of a final result, but, if that result is as close as it was in 2020, that speed will depend on how many mail ballots are returned on or just before Election Day. With days left before the election, less than 45% of mail ballots have been returned, according to the University of Florida’s Election Lab.

Another sign for who will win an Electoral College majority may come from a state not currently seen as a decisive swing state. Florida also reports its results at 7 p.m. and, because it allows mail ballots to be processed and counted before Election Day, it is highly efficient in reporting full results. If Florida — which swung for Trump in 2016 and 2020 — is too close to call at this point, it’s almost a given that Harris is having a good night.

7:30 p.m.: North Carolina

Like Georgia, the winner of the North Carolina presidential race in 2020 was not called for a week after election day. Trump won it narrowly by about 74,000 votes. What delayed the final tally back then was, like in Georgia, the large number of mail ballots and the narrow margin between the candidates.

But mail voting is down significantly from four years ago, with around 413,000 ballots requested this year compared to a little more than 977,000 returned and accepted in 2020.

However, North Carolina Republicans have also heavily restricted the ability of election workers to process and count not only mail ballots, but in-person early votes via new laws passed in 2023. Where election workers could previously process and count both mail ballots and in-person early votes before Election Day, they now must wait to do both until the polls close at 7:30 p.m. on Election Day. This is significant, as a huge chunk of the state’s vote count comes from early in-person voting. So far, nearly 1.9 million North Carolinians have voted early in-person — or around one-third of the state’s total turnout in 2020.

“Those who watch election results in North Carolina have come to expect a large chunk of results very soon after polls close,” Karen Brinson Bell, executive director of the North Carolina State Board of Elections, said in a statement in February. “That will not happen this year.”

One other change made in North Carolina that will affect when a winner will be declared is to the mail ballot receipt deadline. In 2020, mail ballots in the state could be counted if they were postmarked on or before Election Day and received within the next nine days. Republicans in the state legislature, however, required that mail ballots only be counted if they are received prior to the close of polls on Election Day.

The possibility of outstanding ballots stuck in the mail for nine days after the election is one reason why Trump was not declared the winner until 10 days after Election Day. That can’t happen this time.

8 p.m.: Pennsylvania

Pennsylvania delivered the necessary electoral votes for Biden to officially clinch the race in 2020 when it was finally called four days after the election. Like many other states, it took time to project a winner in the state due to heavy mail voting during the pandemic, and because Republicans refused to change the law to allow election officials process and count ballots before Election Day.

Republicans in the state legislature have maintained that stance. State Senate Republicans refused to consider a bill to allow pre-Election Day ballot processing that had passed the Democratic-controlled House on a party line vote in May, meaning officials can only start counting ballots after polls close on Election Day.

So far, Pennsylvania voters have requested more than 2 million mail ballots. That’s down from 3 million in 2020, but is still a lot for election officials to process beginning on Election Day. This means that vote-counting could take time in the state many view as the keystone for the electoral college winner. Unless Harris or Trump runs away with the state, don’t expect a call on election night.

9 p.m.: Arizona, Michigan, Wisconsin

In 2020, Michigan was called for Biden in the evening of the Wednesday after Election Day. Among the swing states that year, Michigan counted its crush of mail ballots somewhat faster because poll workers in some cities could process those ballots beginning the day before the election. Poll workers in Michigan should be able to count ballots even faster this time after voters and Democratic Party legislators enacted sweeping constitutional amendments and laws reforming the state’s election code in response to Trump’s effort to undo the state’s election.

The most crucial change among them is that large jurisdictions can now begin processing and tabulating mail ballots up to eight days before the election. This means that Wayne County, home to Detroit, can pre-process ballots early to allow them to be quickly counted on election night after the polls close, which is at 8 p.m. for most of the state, but 9 p.m. for a small part of the upper western portion.

Election workers already did this in Wayne County during a primary election in August. The county was able to report up to 80% of its mail ballots by 10:30 p.m. on election night thanks to this change, according to VoteBeat.

This should allow the state’s reporting to avoid the optics of an extremely lopsided overnight Blue Shift (not that there’s actually anything wrong with that) that Trump and Republicans used for their false claims of fraud.

Another change that should speed things along in Michigan is the expansion of in-person early voting. Although voters could vote early in person in 2020, they had to do so with an absentee ballot that would be subject to the same limitations on processing and tabulating as mailed ballots. Now, early in-person votes can be immediately scanned into the system on Election Day and reported as soon as the polls close.

Wisconsin, on the other hand, made no such changes. That’s largely due to the fact that Wisconsin’s legislature remains firmly in the hands of Republicans, who, for whatever reason, do not want to speed up the counting of ballots on Election Day.

In 2020, Wisconsin was called for Biden in the afternoon of the day after Election Day — a few hours before Michigan. The number of mail ballots should be lower this year than in 2020, but the counting process will be the same. That could delay the reporting of a winner until the next day if the election is as close as it was in 2020 or 2016, both years in which the state was decided by under a point and a half.

Determining a winner in Arizona, however, may take longer. In 2020, Biden was projected to win the state in the afternoon on the day after the election, but other calls in recent close races in the state have not been so quick. The Senate race between then-Democrat Kyrsten Sinema and Republican Martha McSally in 2018 took a week to resolve. It took six days after the 2022 gubernatorial election before Gov. Katie Hobbs, a Democrat, was declared the winner over Republican Kari Lake.

The main reason why election calls can be drawn out in Arizona is because a very large portion of the state’s voters hand-deliver their absentee ballots — which they call “early ballots” — on Election Day. These “late early ballots” accounted for nearly 20% of all votes cast in Maricopa County, the state’s most populous county, in 2022. Arizona law requires election workers to wait to open and process these ballots until the polls close and all voters have left the polling location. This can delay this process from beginning for an hour or more.

Arizona Republicans added an additional step in February that will likely draw out this process even further. County election officials now must count and report the number of ballots at the voting location before those ballots are then transported to a central processing location.

For these reasons, Maricopa County supervisors warned that achieving a full count of the likely 2 million-plus votes counted there will take between 10 and 13 days. That doesn’t mean it won’t be possible for the press to project a winner before then, but don’t hold your breath.

10 p.m.: Nevada

Nevada is the final swing state to see its polls close on election night. The race there is expected to be extremely close, and a call for a winner is highly unlikely for a few days after the election.

The state adopted all-mail voting with in-person options following the pandemic, which means that, like Arizona, ballots received on or after Election Day will take time to process and count. Nevada also allows ballots postmarked by Election Day to count if they are received within four days of the election. So, while election officials can open and process ballots prior to Election Day, these late ballots could push any call in a tight race off for days.

That is what has happened in many of the top-billed statewide elections. In 2020, Biden was declared winner of the state a few hours after Pennsylvania delivered him the Electoral College win four days following the election. The 2022 gubernatorial race between Democrat Steve Sisolak and Republican Joe Lombardo was similarly not decided in Lombardo’s favor for four days. Meanwhile, Sen. Catherine Cortez Masto (D) was not declared the winner of her race against Republican Adam Laxalt until five days after Election Day in 2022.

If the race is as close as polls say, do not expect a call until at least the weekend.