It's certainly been a long and winding journey, but Election Day 2024 is finally here!

This year's presidential contest started as a rematch between President Joe Biden and former President Donald Trump, with the two matching up closely in the polls --- and in their historic levels of unpopularity. The summer saw no shortage of drama and upheaval as a disastrous debate performance by Biden brought calls for him to drop out of the race to a fever pitch. Shortly after, Republicans held their convention and rallied around Trump in the face of an assassination attempt By the time the Democratic convention rolled around, Biden had bowed out, and the race had reset itself with Vice President Kamala Harris as the Democratic standard-bearer.

One place where the race remained remarkably stable, though, was in the polls, which fluctuated by just a few percentage points over the span of several months and two different campaigns. Heading into today, the contest between Trump and Harris is a virtual toss-up, and the polls are close enough that the race could very well be decided by a single state or even result in an Electoral College tie. Of course, we're also a normal polling error away from a blowout for either candidate. And after two consecutive presidential elections in which polls underestimated Trump's support, a question on every election watcher's mind is whether the same will be true this year.

Looking downballot, the outcome is similarly uncertain in the U.S. House of Representatives, where Republicans are hoping to defend their narrow majority after a tumultuous couple years of their own. (Raise your hand if you googled "who is Mike Johnson" around this time last year.) On the other hand, Republicans are a clear favorite in the Senate in light of a map stacked against vulnerable Democrats.

Plus, hundreds of other elections will be decided today too --- among them, 11 governor's offices are up for grabs, and a wide slate of ballot measures could reshape the landscape for abortion rights, how Americans vote, and more.

As always, we're here to serve as your trusty guides throughout the day (and night, and week), with info on what to look out for and how to make sense of the results as they come in. Thanks for joining us!

If it’s after 5 p.m. Eastern on Election Day, it’s exit poll time! If you’re watching the news or scrolling social media tonight ,you’re likely to encounter findings from this mega-poll of voters throughout the night (and coming weeks). But there are some reasons to take what you see, especially early, with a grain of salt.

The exit poll is a survey of voters nationally and in key states that asks people questions like who they voted for, when they made up their mind and why they voted the way they did. The exit poll is conducted by Edison Research (a survey research, voter data and election returns company) and sponsored by a consortium of news networks in the U.S. (ABC News is one of them.) ABC News will be reporting exit poll results nationally and in 10 states: the seven battleground states (Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin) plus Florida, Ohio and Texas.

Long ago, the exit poll only interviewed people in person as they left their polling places after casting ballots in person on Election Day. With the rise of mail-in and in-person early voting, the pollsters and statisticians behind the exit poll added telephone interviews to account for early and mail-in voters.

The exit poll is an incredible feat of engineering and a rich source of data on voter behavior in America, and you can expect it to be cited frequently after the election as a measure of “ground truth” (or at least one of the highest-quality estimates available) about how and why people voted. However, at the end of the day, the exit poll is just a very detailed survey, so it is not infallible. In particular, the way it is conducted warrants two main caveats:

First, the results of the exit poll can and will change over time, especially at the subgroup level. The earliest results of the exit poll are essentially toplines and crosstabs from a very large poll of voters, but which contain a lot of guesses about the eventual demographic composition of the country. As the votes roll in over the course of the election night (or week), the pollsters behind the scenes adjust the results of the poll to match the results of the election.

As a result, the findings of the exit poll can and do change as more votes are counted, especially for subgroups. In Wisconsin in 2020, for example, preliminary exit poll results had Trump +1 among men. In final data (weighted Wednesday morning), Trump was +10 among men. Overinterpreting the poll — say, if you had hitched your horse to the wagon of low or no gender gap in the electorate — risks setting up narratives that are swiftly knocked down with actual data.

The second word of caution is to remember the exit poll is just one imperfect estimate. Yes, it is generated with a lot of data and care, but misspecified weights or sampling noise can impact results just like with any other poll. Interpretations of the final exit poll results should be used with caution. As a result of all these caveats, 538 rarely cites exit polls, and we prefer to wait for actual results before wedding ourselves to narratives. If you are going to cite the exit poll, we recommend waiting until it has been at least somewhat weighted to be representative of actual election results.