Stephanie Scarbrough/AP
A person marks their ballot as their child looks on at the polling place at Tysons-Pimmit Regional Library in Falls Church, Virginia, on Thursday, October 31, 2024.
CNN  — 

It’s decision day in America’s battle for the White House and control of Congress – even if the results could take days or weeks to sort through.

Vice President Kamala Harris and former President Donald Trump are battling over seven swing states: Michigan, Pennsylvania and Wisconsin, the three Great Lakes states that make up the “blue wall” that Trump cracked in 2016 but President Joe Biden carried in 2020, and Arizona, Georgia, Nevada and North Carolina, the four Sun Belt battlegrounds.

If Harris wins, she would make history, becoming the first woman, first Asian American and first Black woman to win the presidency. A Trump victory would also be historic: He’d join Grover Cleveland as the only presidents to serve non-consecutive terms. He would do so after becoming the only president ever impeached twice, and the only former president ever convicted of felony crimes.

There is much more being decided Tuesday, including five states – Arizona, Florida, Missouri, Nebraska and South Dakota – voting on whether to turn back abortion bans with constitutional amendments.

Republicans hope to take advantage of a favorable Senate map, with Democrats defending seats in the red-leaning states of Montana, Ohio and West Virginia. The party’s hopes of holding onto its narrow House majority winds from the coast of Maine through New York’s Hudson Valley, the rolling hills of Virginia’s Piedmont, a “blue dot” in Nebraska and into California’s Orange County, where the political ebbs and flows of the Trump era have been on vivid display.

The initial results in the hours after polls close might not be determinative. States decide their own election procedures, and the order in which states count early, mail-in and Election Day votes varies across the map – as does how quickly certain cities, counties and regions report their results.

Here are seven things to watch on Election Day:

The most likely paths to 270 – and the presidency

Americans have become increasingly accustomed to incredibly close presidential races. In 2000, 2016 and 2020, the results came down to tens of thousands of votes. This race is expected, if the polling is correct, to fit in that mold.

That means, in the simplest terms, that there are seven states to watch on Tuesday night – and possibly beyond.

Arizona and Georgia went for Biden in 2020 after being reliably Republican for a generation. Democrats also won Nevada four years ago, though their margins there have been diminishing. Biden swept the “blue wall” states of Pennsylvania, Michigan and Wisconsin in 2020. Trump did the same in 2016. The only 2024 battleground Trump won in the last election was North Carolina. It’s expected to be a close race there again.

So how should armchair analysts be gaming it out? With the usual caveat that anything can happen, and, in recent years, it often has – here are a few potential paths for Harris and Trump, respectively:

For Harris, the map is in many ways simpler. Repeat Biden’s “blue wall” sweep and she is almost surely destined for the Oval Office. That takes into account the expectation that she will win an electoral vote in Nebraska and lose another in Maine, two states that dole out electoral votes to both the statewide and congressional district-level winner.

If the “blue wall” cracks and Pennsylvania goes for Trump, her path becomes more complicated. The commonwealth has 19 electoral votes. Harris would need to make up that number by winning either Georgia and North Carolina, which both have 16. If she can only split the pair, Nevada and Arizona could become deciders.

Like Harris’, Trump’s map leans hard on Pennsylvania. If he wins there while holding on to North Carolina, the former president would only need Georgia to swing back to him to reach 270. Victory without Pennsylvania, for Trump, likely means the “blue wall” cracks somewhere else.

In that scenario, Trump would likely need to win Michigan or Wisconsin and supplement it with a dominant performance across the Sun Belt, from Georgia on the East Coast to Arizona and Nevada out west.

The red and blue ‘mirages’ to expect

Four years ago, with Trump undermining many Republican voters’ confidence in mail-in ballots, the early hours after polls closed showed a “red mirage” in several key swing states – with the initial returns looking better for Trump than the final results would show hours or days later.

A “mirage” in election results typically is the result of several factors, including geography (small, rural counties that tend to favor Republicans have fewer votes to count and report their results faster) and the types of ballots being counted — a reality to keep in mind if the early results from Michigan don’t include Detroit, and if those from Nevada don’t include Las Vegas.

States and counties also often count and report one method of voting – early votes, Election Day votes and mail-in ballots – at a time. When one party tends to perform better with a certain method, as Democrats did with mail-in voting in 2020, the results can shift as elections officials move from counting one type of vote to another.

Another factor – and one that helps to explain why a state the size of Florida reports its results so quickly – is how mail-in ballots are processed.

States set their own rules on when mail-in ballots can be opened. Two “blue wall” states, Pennsylvania and Wisconsin, prohibit local elections officials from beginning to process ballots until Election Day, slowing the counting process there compared to states like Florida, where they are opened ahead of time.

Those state laws led to a huge jump in Biden’s favor in 2020 in the early-morning hours in Wisconsin, when deep-blue Milwaukee reported a huge batch of mail-in votes that went overwhelmingly in the Democrat’s favor.

Other swing states have made changes since 2020. In Georgia, a new election law will likely lead to fewer mail-in votes and more early votes – which could mean quicker results. In North Carolina, mail-in votes are no longer accepted after Election Day, which could be a critical distinction if the outcome is on razor’s edge. And because most of the mail-in and early votes will be counted first there, the Tar Heel State could see a “blue mirage.”

In Arizona, a state that overwhelmingly votes by mail, those ballots are counted in the order they are received. That means Harris could see a sizable early lead, before late-arriving mail-in ballots and Election Day votes (both of which favored Trump in 2020) are counted.

Early indicators from the early reporting states

A definitive result in the presidential race may not come on Tuesday night, or even Wednesday for that matter, and the early counts from battleground states could be difficult to parse. But there will be some insight to glean from smaller contests, most notably House races in even solidly blue or red states.

Virginia, which has gone blue in presidential elections since Barack Obama’s first run, is typically one of the first states to report, and New York, despite being a Democratic stronghold statewide, has been targeted by massive spending from both parties focused on a series of swing-y suburban House contests.

In 2016, Virginia offered the first sign that Hillary Clinton was in trouble.

By then, the commonwealth had become reliably Democratic in presidential races but Clinton was barely scraping by for most of the night. She’d eventually win by about 5 points (Biden won it by more than 10 points in 2020). The reelection of then-Rep. Barbara Comstock that year, in a seat many Democrats were hopeful about flipping, also augured bad things for Clinton and her party.

This time out, Virginia’s 7th Congressional District could be the canary in either side’s coal mine. Victory for Eugene Vindman, the Democratic nominee, and a clear lead for Harris could spell trouble for Trump up and down the ballot.

New York, too, might seem like an unlikely place to go in search of national trends. But the state saw a “red wave” of sorts in 2022, with Gov. Kathy Hochul winning by only about 7 points and Republican House candidates flipping seats outside New York City.

This year, freshmen GOP Reps. Anthony D’Esposito, Marc Molinaro and Brandon Williams, in central New York, all enter Election Day looking vulnerable. Other first-term Republicans like Reps. Nick LaLota, on Long Island, and Mike Lawler, north of the city, are favorites in their races, but hardly locks for reelection.

The results in those races, whether Republicans or Democrats beat the expectations laid about above, will be almost as important as how they unfold. The fate of a statewide ballot measure, known as “Prop 1” or the “Equal Rights Amendment,” could also give voters across the country a sense of where things are headed. (The measure is expected to pass, but its margins outside of New York City could be telling.)

Simply put, both parties will be watching the returns closely for signs of a pink wave, or surge in turnout among women voters, that could be an early warning sign for Trump and Republicans anxious about a gender gap in polling that shows Harris with, in many cases, a larger lead among women than Trump has with men.

Can Republicans flip the Senate?

If the presidency and control of the House seemed like coin flips heading into Election Day, the fight for control of the Senate is expected to be much less dramatic.

Democrats currently hold a slim majority, with 51 senators – four of them independents – caucusing under Majority Leader Chuck Schumer of New York. For the party that wins the White House, 50 would be enough to secure a majority (because the vice president casts tie-breaking votes), but Republicans are on the offensive this year thanks to a friendlier map.

West Virginia, in particular, looks like a lock to swing to Republicans. In Montana, Democratic Sen. Jon Tester is in a tough race with GOP nominee Tim Sheehy. Ditto for Sens. Sherrod Brown of Ohio, Tammy Baldwin of Wisconsin and Bob Casey of Pennsylvania. Democratic Sen. Debbie Stabenow’s retirement has also made a Senate battleground out of Michigan.

Republicans will likely win a majority if they can flip even one of those seats, so Democrats have next-to-no margin for error, as CNN’s Simone Pathe lays out.

Still, there are a few wild cards in play.

Rep. Colin Allred is running a spirited campaign against Sen. Ted Cruz in Texas, but Democrats haven’t won statewide there in ages. Nebraska Sen. Deb Fischer could also be in some danger, but her challenger, Dan Osborn, is a true independent, so it’s unclear how he would vote in a Senate leadership contest.

Can Democrats win control of the House?

Republicans flipped control of the chamber in 2022 by the slightest of margins. This year, House Democrats – who typically do better in presidential election cycles – need a net gain of four seats to make Hakeem Jeffries, now the minority leader, the House speaker next year.

The fate of the House could take on even greater importance if Trump returns to the Oval Office and Republicans win the Senate. A GOP trifecta would give Trump close to carte blanche to pass his agenda into law. A Democratic majority would serve as a final bulwark against the former – and, in this case, future – president’s policies.

All 435 House seats are on the ballot, but only a handful of races are expected to be close. That means a few select districts will wield a disproportionate impact on the outcome, and CNN’s Terence Burlij listed 10 seats to watch on election night and beyond.

The current GOP majority was, in large part, delivered by swing districts in California and New York – especially on Long Island and north of New York City. Empire State Democrats have, in response, launched massive, coordinated campaigns – one helmed by state leaders and another by a labor-progressive coalition – aimed at winning back seats the party lost in 2022.

But as Election Day neared, other districts of interest emerged. New Jersey’s 7th Congressional District could be especially telling. GOP Rep. Tom Kean Jr. won the seat in 2022 after redistricting made it more friendly to Republicans. Democrats redrew the map with an eye on protecting Reps. Mikie Sherrill and Josh Gottheimer, but effectively squeezed out Tom Malinowski, who lost that November to Kean Jr.

The district was mostly an afterthought when the campaign season began, but many observers now believe Democratic challenger Sue Altman has moved within striking distance of the incumbent. House Democrats’ largest super PAC was convinced enough that it decided to kick a reported $4 million into the race in its final weeks.

It takes 218 seats to make a majority in the House, so no single race will be definitive, but if Altman defeats Kean Jr. – a result that could be known relatively early in the evening – Democrats will see a wave building.

Will Trump declare victory early?

Not only is Trump’s 2020 playbook wide open, he’s added some new pages to the 2024 edition.

The main themes are the same. He’s already accused Democrats of cheating, warned that noncitizens are voting en masse and sowed doubt over mail-in and overseas ballots (where there’ll expected to break against him). The claims are all baseless, of course, but like four years ago there are millions of Americans primed to believe.

And then there is the simple math of vote-counting, which is expected to come under heavy scrutiny – and, in some cases, face outlandish slander – in swing states.

The math is expected to favor Trump in the earlier hours of the count, in part because of which states report and when. In 2020, mail-in ballots, which are not counted until Election Day or even after polls close in some critical states, broke heavily for Biden. That phenomenon created what’s been called a “red mirage” – the appearance that Trump and Republicans are winning big when, in reality, their votes were just being reported first.

It’s not clear yet if that dynamic will repeat itself this year. Trump has encouraged supporters to vote by any means, including mail, after discouraging it in 2020. Democrats, too, could behave differently now that the Covid-19 pandemic is less of a concern.

Still, the question remains: Will Trump declare victory before the race is truly decided? The conventional wisdom, shared by operatives across party lines, is that he will seize on an early lead, like he did four years ago, and announce himself as the president-elect.

That expectation has led Democrats and nonpartisan media to warn Americans that there is a significant possibility that the winner of the presidency will not be known for days after the polls close.

What’s less clear, even now, is whether – and if so, how – Trump and his allies might agitate to hold-up or close-down the process.

Deadlines and disinformation

Trump has long said that elections should be decided on the night they’re held. But doing so would disenfranchise many voters — especially in states where mail-in ballots only have to be postmarked by Election Day to be counted in the days that follow.

It’s a particularly critical distinction in states like California and New York, which aren’t competitive in presidential contests but are home to a swath of House races that could decide control of the chamber. Both states count votes received up to seven days after Election Day, as long as they are postmarked in time.

Most battlegrounds, including Arizona, Georgia, Michigan, North Carolina, Pennsylvania and Wisconsin, require most or all mail-in ballots to be received by Election Day. But those ballots are processed more slowly in Pennsylvania and Wisconsin. And Nevada allows those postmarked by Election Day to be counted as long as they arrive within four days.

Both campaigns will be on close watch for isolated problems on Election Day — well aware that Trump has twisted some of those incidents to bolster his false claims that Harris is cheating.