POLITICO's hour-by-hour guide for watching election returns

The nation is again staring down a presidential race that could very well go into overtime.

The election in 2020 introduced us to the term "election week," when it took nearly 90 hours after the final polls closed four years ago until Joe Biden was definitively declared president-elect. It probably won't take that long this time , though the head of Fox News' decision desk set a similar Saturday time frame as his over/under in an interview with POLITICO Magazine last month.

Even if dawn breaks without a president-elect, the sequence of events on Tuesday night will illuminate the mood of a restless and worn-out electorate, potentially decide control of Congress and should provide clues about who will be taking the oath of office in January.

Here is your hour-by-hour guide to Election Day — whether the race ends that night or not (all times Eastern; note the battleground states are bolded):

5 a.m. Eastern — The first voting begins

The first polls will open beginning at 5 a.m. in some Vermont towns, even though technically, the first Election Day votes are cast at midnight in the small town of Dixville, New Hampshire — home to six registered voters (four Republicans and two independents). This allows the town to close the polls and report the first votes for Kamala Harris or Donald Trump anywhere in the country.

5 p.m. Eastern — Head for the exits

Don't expect results just yet, but we get our first clues about the composition and preferences of the electorate when news outlets begin releasing nuggets from their still-underway exit polls.

There are two voter surveys: the traditional exit poll of in-person interviews with Election Day and early in-person voters, along with supplemental polling of mail voters. That's conducted by Edison Research for the National Election Pool, which includes ABC News, CBS News, CNN and NBC News. There's also AP Votecast, a voter survey without an in-person component conducted by The Associated Press, along with Fox News.

Beginning at 5 p.m., those news networks will begin releasing data from the survey, even though interviews will continue for hours. Since people are still voting everywhere, the results won't characterize the outcome in any way but will include important clues about the race. The surveys may include data on how many voters made their decision in the final week of the race, or what percentage of voters approved of the job Biden is doing as president.

6 p.m. Eastern— Kentuckiana

The first Election Day polls close at 6 p.m., with voting concluding in the Eastern Time Zone portions of Indiana and Kentucky, which includes most of those states' voters. Neither is a competitive state in the presidential race, but early results around Indianapolis could tell us about the race in the suburbs.

Watch the fast-growing and increasingly competitive Hamilton County north of Indianapolis: Trump won it by 20 points in 2016 but just 7 points in 2020. Another sign Republicans there are not big Trump fans: Nikki Haley got 34 percent of the vote in the GOP presidential primary — even though she had dropped out of the race two months earlier.

7 p.m. Eastern — First states close

Parts of: Alabama, Florida, New Hampshire

The first big swing state closes at 7 p.m.: Georgia. And most of the vote should be counted fairly quickly: When the in-person early-voting period ended last week, more than 55 percent of registered voters had already submitted their ballots. But that also means that the early count will likely be more Democratic, with Trump and the GOP catching up later as Election Day votes are tallied.

Meanwhile, despite its well-earned reputation after the 2000 election, Florida is now one of the fastest states at counting ballots.

Not only does Florida count quickly, with the majority of votes likely tallied by the time the panhandle closes at 8 p.m., but it also reports real-time turnout stats on Election Day. Republicans' stronger-than-2020 early-voting numbers have raised questions about whether they're bringing out new voters or cannibalizing their existing electorate. Florida is no longer a bellwether — but it could help answer this question.

7:30 p.m. — Carolina on my mind

Parts of: New Hampshire

Another fast-counting Southern swing-state closes a half-hour later: North Carolina. As in Georgia, expect the first votes (a lot of mail ballots) to lean Democratic, with Trump gaining as the night goes on. Still, most of the votes should be tallied by the end of Tuesday.

Expect a fast call in the state's gubernatorial race, which went from hotly contested to a blowout as scandal-plagued Republican Lt. Gov. Mark Robinson fell hopelessly behind Democratic state Attorney General Josh Stein in the polls.

And Ohio, which like Florida has lost its presidential swing state status, has a closely watched Senate contest. Democratic Sen. Sherrod Brown may be carrying the fate of his party's embattled Senate majority with him into his matchup with Republican Bernie Moreno. The GOP needs to net two seats Tuesday — or one seat plus the presidency — to win control of the Senate.

By this point in the night, Republicans should already be halfway there, when they flip their first seat in West Virginia. GOP Gov. Jim Justice has a huge lead in the polls in the race to replace retiring Sen. Joe Manchin (I-W.Va.).

8 p.m. — Blue Wall check-in

Parts of: Kansas, , North Dakota, South Dakota, Texas

All of Pennsylvania and most of Michigan's polls close at 8 p.m. Unlike Georgia and North Carolina, they won't report very quickly. But it will likely be faster than it was in 2020.

Michigan — where a small part of the Upper Peninsula stays open for an extra hour — has been tabulating its early votes and expects to finish counting late Tuesday night. Four years ago, the state wasn't called for Joe Biden until late Wednesday afternoon, even though Biden won it by 3 percentage points.

Pennsylvania famously wasn't called until nearly four days later. That's unlikely to happen this time, but it will still likely take until Wednesday to discern a winner if the race is close.

Both states have competitive Senate races. In Pennsylvania, Democratic Sen. Bob Casey is seeking to hold off Republican Dave McCormick. And Democratic Rep. Elissa Slotkin is hoping to topple her Republican rival, former GOP Rep. Mike Rogers, in a close race in Michigan.

In Maryland, former GOP Gov. Larry Hogan hopes the state's Senate race breaks so significantly from the top of the ticket — Biden won it by more than 30 points in 2020 — that he can beat Democrat Angela Alsobrooks, but polling in the race's final weeks looked daunting for the moderate Republican.

In other states, keep an eye on the electoral vote out of Maine's 2nd District, where Trump is favored, and the governor's race in New Hampshire, where former GOP Sen. Kelly Ayotte is seeking a comeback eight years after she was ousted from her seat.

8:30 p.m. Eastern — Little Rock in a big pile

Only one state closes at 8:30: Arkansas, which hasn't voted Democratic since its favorite son, Bill Clinton, was president.

9 p.m. Eastern — The Heartland of the matter

Another major moment in the race. There's little expectation that Arizona will be called Tuesday night, given the prevalence of late-arriving mail ballots, which trend Republican. But we'll get our first look at the presidential race and a key Senate race in the state when the first results are released (which isn't until an hour after polls officially close).

Meanwhile, most of Texas closes at 8 p.m. By the next hour we should have a good idea of how close Democratic Rep. Colin Allred comes to beating GOP Sen. Ted Cruz. Given the daunting math elsewhere, Democrats may need Allred to pull the upset to keep their majority.

Another option: Independent Dan Osborn has been within striking distance of GOP Sen. Deb Fischer in Nebraska. An Osborn victory would scramble the Senate math, since he's vowed not to caucus with either party.

10 p.m. Eastern — Tester on the brink

Parts of: Idaho, Oregon

Polls in the final presidential battleground state, Nevada, close at 10 p.m. Eastern. But don't expect a quick result: In the 2022 Senate race, which Democratic Sen. Catherine Cortez Masto won by 1 point, it took six days to call the race.

The state's other Senate seat is up this year, and it could similarly take a while to declare a winner between Democratic Sen. Jacky Rosen and Republican Sam Brown.

But the most pivotal Senate seat is not in a competitive presidential battleground. Democratic Sen. Jon Tester is trying to defy Montana's partisanship and hold off Republican Tim Sheehy. If Republicans pick up Montana and hold all their other seats, they have the Senate no matter who wins the White House.

11 p.m. — Focus on the battlegrounds

At this point in the night, we're mostly counting the battlegrounds that have previously closed. By 11 p.m., we could very well have calls in Georgia and North Carolina. If Harris picks off either it will likely be due to strength with Black voters.

Trump victories in both, however, could essentially refocus the race on the crucial (and slower-counting) Blue Wall states, which would become must-wins for Harris.

The biggest Electoral College prize, California's 54 electoral votes, will be awarded promptly when polls close at 11 p.m. On the other hand, a half-dozen competitive House races there that could hold the key to the majority in that chamber could take weeks to resolve, thanks to the state's slow count of its mail ballots.

12 a.m. Eastern — In the midnight hour

Parts of: Alaska

It's Wednesday, and we're probably still waiting on five of the seven battleground states. But by midnight we could be close to calls in Michigan and Wisconsin, as long as the margin between the candidates is decisive.

1 a.m. Eastern — All closed up

The final polling places in the United States, in the Aleutian Islands, close at 1 a.m. Eastern Time. Alaska takes a while to count — it wasn't called until eight days after the election in 2020 — but isn't truly competitive.

Four years ago, the 1 a.m. hour was when the electoral vote in Nebraska's 2nd District — the Omaha-based "blue dot" — was called for Biden. This time, if Michigan and Wisconsin aren't called by 1 a.m., it might not be too much longer.

If the race is as close as it appears to be, we'll probably go to bed early Wednesday morning still waiting on three states: Arizona, Nevada and Pennsylvania. Those states' 36 electoral votes may very well decide who wins the presidency.