The way the US counts votes is unique. In fact, there is no central system for counting votes, but rather tens of thousands of them in local electoral districts across the country.

To figure out who won where, the Guardian and many other newsrooms rely on the Associated Press, which has been calling U.S. elections since 1848. (Some television networks, such as CNN, use their own analysis of the results to make voting decisions.)

“Two years after the AP was founded, in 1848, we decided there needed to be a trusted, impartial source of information about who the country had elected its new leaders,” said David Scott, vice president and head of news strategy and operations at the AP, said the Guardian.

The AP's process for monitoring election results has been updated multiple times over the past 176 years. This year, the AP will rely on 4,000 reporters to report vote totals.

How can the AP predict who won when the votes have yet to be counted? What is a “red mirage” and a “blue shift”? Read more about the Guardian's interview with Scott, edited for clarity and brevity:

What key sources of information does the AP decision team rely on to make decisions?

In this general election, we'll have about 4,000 vote count reporters working in county election offices, city and town election offices, Louisiana parish election offices… They're calling a group of about 800 people who make up our vote entry team, people who get those numbers and verify. And then there is a dedicated quality assurance team that makes sure we are as confident as possible that the results are accurate.

Some states and some counties have direct feeds that allow us to get votes as they are reported. Others publish their results on websites, and sometimes we can extract them automatically. One of my favorites is that there's a county out there that writes a photo of their vote count results on a whiteboard and posts a picture on Facebook, so we need to get them there.

That's what's so funny about the whiteboard. Even the reporters who literally cite the results seem pretty old-fashioned.

Yes, I often get asked, “Why don’t you just have an app for that?” We actually enjoy talking to these vote counting reporters. It gives us the ability if someone calls a number and says, “Hey, our system showed that you just reported that there are more votes for this candidate than there are registered voters in this county,” you still can “Go back and check again?”

We are able to easily perform this verification in real time and it helps avoid fat finger errors. So it's a little analog, but we think it's the process that still works best for us.

A question that comes up every election cycle is: How can the AP determine the winner of a race when there are so many votes left to count?

The question we ask ourselves before announcing a winner is: Is there any chance the closing candidate can catch the leader? If there is a possibility, then we don't mention it. We are waiting.

Sometimes it's really obvious. People have a very large lead, a lead so large that there aren't enough votes left to count it, and that allows us to move forward. Sometimes races are very competitive and there are simply no votes left to count.

And how does your team explain the “red mirage” or “blue shift”.“, when the first group of reported votes may be more biased towards one party?

It's probably best to illustrate this with an example. In a state like Virginia, the first-reported votes generally come from the more rural areas of the state, and those votes tend to favor Republicans. The final votes tend to come from Northern Virginia and the Washington, D.C. suburbs, and those votes tend to favor Democrats.

This is absolutely something we take into account when considering whether a winner can be announced. States are unique and counties vary within states. We must therefore take this geographical diversity into account.

Why are some places slower to report results than others? Can you give an example?

Florida really transformed its election system after 2000, and it happened very quickly. It's very efficient in all counties so they can count very quickly and that was something they made a priority. California values ​​maximum participation. They allow mail-in ballots to arrive long after Election Day as long as they are postmarked by Election Day, and they send everyone a mail-in ballot.

Both decisions are completely valid, but these decisions affect how quickly we learn the results in both states.

In 2020we waited days in Pennsylvania for the results. Do you expect that to happen again, or is there another state that could be behind in the count this year?

I don't make political predictions. All I'm saying is that how long it takes before we know who the next president will be depends entirely on how close the race is, and that's up to the voters.