GEOFF BENNETT: So, candidates are campaigning, absentee ballots are being mailed out, early votes are being cast.

It's all leading to November 5 and one big question, who won?

But to find that out, votes actually have to be counted.

Our Lisa Desjardins takes a closer look at how the Associated Press keeps track of thousands of competitive races and makes the call.

LISA DESJARDINS: For decades, millions of viewers like you have turned to the "PBS News Hour" on election night... GWEN IFILL, Former "PBS News Hour" Anchor: Polls have just killed.

LISA DESJARDINS: ... to see history and to learn the future of the country.

JIM LEHRER, Co-Founder and Former Anchor, "PBS NewsHour": Now the Associated Press, we can report, has officially declared President Clinton.

LISA DESJARDINS: And for decades, PBS News and hundreds of other news outlets have relied on the Associated Press to count votes and call winners.

JUDY WOODRUFF: We're hitching our wagon to the AP.

LISA DESJARDINS: It is a monumental task.

This year on election night, the AP's team of journalists will track over 5,000 competitive races, president, Congress, mayors and many, many more.

DAVID SCOTT, Vice President of News Strategy and Operations, Associated Press: We like to call it the single biggest act of journalism there is.

LISA DESJARDINS: David Scott is the AP's vice president of news strategy and operations.

He oversees the election team.

DAVID SCOTT: Our number one most important goal on election night is to be 100 percent right in our race calls.

LISA DESJARDINS: One hundred percent.

DAVID SCOTT: That's our standard.

We do care about speed, but only as a secondary factor.

It's never compromise on the accuracy in an effort to be faster.

LISA DESJARDINS: The AP has been counting the vote for 175 years, including when vote totals from some places were sent back on horseback.

DAVID SCOTT: We are really, really proud of the role that we play in the democracy.

The founders didn't think through how we would get from poll close to Inauguration Day.

Who's going to count up the votes and who's going to say that there's a winner?

And so AP decided back in 1848 that we'd jump into that process.

MAN: And we got votes.

LISA DESJARDINS: We watched the process at the AP's Washington bureau on one of the final primary nights of this year.

MAN: There's usually a rhythm in it.

And it usually starts off slow.

LISA DESJARDINS: In a quiet corner of the mostly empty newsroom, the election team was keeping track of about three dozen races in just one state, deciding when to call a winner in each.

MAN: The check mark.

There it goes.

LISA DESJARDINS: But on general election night, this newsroom will be filled, handling a slate of races 150 times larger.

No matter the scale, the fundamentals remain the same.

MAN: We will get to a certain point where we will actually get a model recommendation.

LISA DESJARDINS: The AP calls races when it is certain that statistically only one person can win.

DAVID SCOTT: We're looking to know one thing.

Can the trailing candidates catch up?

And once we're certain that they can't, then that's when we call the race.

LISA DESJARDINS: That real-time call takes months of planning, years of experience and data, lots and lots of data.

I see it flashing green too.

Does that mean you're getting updated votes at that point?

MAN: Yes.

LISA DESJARDINS: OK.

Starting with the official vote count.

That's the actual tally in each race.

With tens of thousands of polling places across the country, yes, it is a big job.

DAVID SCOTT: We will have people in place at county election offices, so it's about 4,000 reporters out across the country.

And that's just one of the ways that we collect the vote.

We also take in data feeds.

We're scraping Web sites.

We're looking at Web sites and manually entering them.

We're always looking to get the vote count from as many sources as we can and never from just one source.

MAN: Some places would rather you get it off their Web site.

LISA DESJARDINS: But as the numbers come in, the AP also needs to figure out how many votes are left to be counted.

How close is this to a final result?

MAN: So there's less than 1 percent of those counted.

LISA DESJARDINS: To do that, the AP carefully estimates the total number of ballots expected to be cast in each state.

As voting methods have shifted, this has become trickier.

Thirty years ago, fewer than one in 10 voters cast their ballot before Election Day.

That number grew steadily until the pandemic upended the 2020 election, and nearly 70 percent of votes were cast early, either in person or by mail.

Polls suggest half of voters may do the same this year.

DAVID SCOTT: We're looking at how many people are registered.

We're looking at what was the turnout in the past comparable election.

We're looking at how many advance votes are already in the ballot box, information we get from a lot of states.

And we sort of plug that all into a model where we are trying to estimate how much vote has been cast.

LISA DESJARDINS: So, in real time, you can adjust... DAVID SCOTT: Absolutely.

LISA DESJARDINS: ... is this going to be a bigger election than we thought or smaller?

DAVID SCOTT: Right.

And then, once polls close and we actually start getting ballots in, those actual returns feed into the model as well and we make adjustments.

So you will see that estimate change over the course of the night.

That's not a problem.

That's us adjusting to the data.

LISA DESJARDINS: Further complicating the process, states count and release different types of votes in different order.

In battleground Arizona, they start counting mail votes as they're returned, but they don't start releasing results until an hour after polls close.

In Pennsylvania, early ballots are not processed at all until Election Day.

In New Hampshire, they aren't counted until after polls close.

DAVID SCOTT: You're looking for patterns on election night when we're calling races.

Are there a class of early ballots that have yet to be counted, and what do we expect those early ballots to say about the course of the election?

If we had to wait for 100 percent of all ballots to be counted, we wouldn't know what has taken place in the election for weeks after Election Day.

LISA DESJARDINS: If the presidential race is close, as many expect it to be, it may still take days to know the winner, just like it did in 2020.

It says it's a zero percent confidence score.

MAN: Yes.

LISA DESJARDINS: What does that mean?

MAN: That means that we're not ready to call it.

LISA DESJARDINS: As the AP decision desk works to call the race as quickly as possible, all the data flow into a computer model.

WOMAN: Starting to get a pretty good pattern.

LISA DESJARDINS: But it's still analyzed by real people.

And you see no way that the other candidates could win?

WOMAN: No, no.

LISA DESJARDINS: Those observers have added data from another unique way that AP gets election information, its VoteCast system.

That is voter surveys of more than 120,000 people across all 50 states.

The AP survey is an update and twist on traditional exit polls, where someone would stand outside of polling places and ask people who they voted for.

AP now accounts for people who vote early or by mail or who stay home entirely.

To do that, the VoteCast team conducts surveys online and on the phone all the way up to when polls close.

The data help explain who voted and why.

DAVID SCOTT: We're able to analyze smaller slices of the electorate with a margin of error that means we can act on it.

So we're able to look at Hispanic voters or African American voters or young voters, but then also combinations of those voters in a way that helps us potentially get to a race call sooner or understand the way that the electorate is shaping up in a level of detail that didn't exist before.

LISA DESJARDINS: All that, 4,000 reporters getting real-time results, months of estimating the likely turnout, and surveys of over 100,000 people, it all leads to the big moment and the actual race call.

DAVID SCOTT: They're doing it right now.

David and his team weigh in.

Then the major calls, including for president in close states, go to the desks of executive editor Julie Pace and Washington bureau chief Anna Johnson.

ANNA JOHNSON, Washington Bureau Chief, Associated Press: We will make sort of that final sign-off to say, yes, let's go with it, or often we have some questions and things we want to answer.

Have we considered this?

Have we looked at that?

But, ultimately, it's to say yea or nay, we're ready to go.

LISA DESJARDINS: What kind of pressure do you feel?

ANNA JOHNSON: There's ultimately a lot of pressure in it.

On the other hand, we know we're right.

We know that information is correct.

Our goal then is just to get it out to the world.

LISA DESJARDINS: In those moments, even on a busy general election night, the crowded newsroom can feel as small as it was for a single state's primary election.

ANNA JOHNSON: And most of those times it's fairly calm, and I think there's just a lot of focus in those moments.

LISA DESJARDINS: So it's quiet?

ANNA JOHNSON: It can be actually somewhat quieter, because people realize we're in a moment and everyone needs to focus and keep -- pay attention.

LISA DESJARDINS: Focus and attention the AP's biggest act of journalism, a responsibility grounded in a massive, careful, hands-on operation and a mission they take seriously, no matter which election they're watching or how long it takes to call the winner.

DAVID SCOTT: There's always a moment every general election where, for a very small amount of time, you're the first person to know who's going to be the next president.

You cherish that and then you get down to business calling that race.

LISA DESJARDINS: For the "PBS News Hour," I'm Lisa Desjardins at the AP decision desk in Washington.