Americans go to the polls Tuesday to determine whether President Donald Trump will be elected to another four-year term or Democrat Joe Biden will replace him in the White House.

Here are several things to watch for Tuesday.

History has already been made.

More than 93 million Americans have already cast ballots, the most in U.S. history. Trump will either become the first president to be reelected after he was impeached by the U.S. House of Representatives, or Biden will become, at the time of his Jan. 20, 2021, inauguration, the oldest man to work in the Oval Office.

Whose turnout approach wins?

The two parties took wildly different approaches to contacting voters amid the pandemic.

Democrats stopped knocking on doors in the spring, going all-digital and phone. They resumed limited in-person contacts in September. Republicans continued traditional field work the entire campaign.

The GOP can point to success in increasing their voter registration in battleground states. Democrats can point to their early voting success, including from notable slices of new voters. But only the final tally will vindicate one strategy or the other.

When will the race be called?

Absentee voting amid the coronavirus has changed the vote-counting timeline, and there aren’t uniform practices for counting those ballots. That makes it difficult to predict when certain key battlegrounds, much less a national result, could be called.

Election workers must remove the ballots from their envelopes, check for errors, sort them and flatten them — all before they can be run through scanners the moment polls close and be tabulated. In states with well-established vote-by-mail programs, this processing happens weeks before Election Day. The results are often released quickly.

But several states did not have this system in place before this year, and laws on the books prohibited election officials from processing the ballots well in advance of Election Day. Without a head start, there’s virtually no way to process and count all the mail votes on Election Day, while also counting all the in-person votes.

There are three important battlegrounds with restrictions on when the mail vote can be processed: Michigan, Pennsylvania and Wisconsin.

In those states, Republican-controlled legislatures have resisted pleas from election officials to update the laws to allow for a speedier count. (The Michigan Legislature allowed processing to begin 24 hours before Election Day in cities, but election officials say that’s not enough of a head start.) Instead, they will initially report in-person votes — expected to heavily favor Trump — and gradually update with the more Democratic-leaning mail ballots later.

Early returns, meanwhile, could show divergent results. Biden is expected to lead comfortably among early voters, for example. Trump is likely to counter with a lead among Election Day voters. Depending on which counties report which batch of votes first, perennially close states could tempt anxious partisans to reach conclusions that aren’t necessarily accurate.

Will voting be peaceful?

Each major party can install official poll watchers at precincts. It’s the first time in decades Republicans could use the practice after the expiration of a court order limiting their activities. So it’s an open question how aggressive those official poll watchers will be in monitoring voters Tuesday or even challenging eligibility.

The bigger issue is likely to be unofficial “poll watchers” — especially self-declared militias. Voter intimidation is illegal, but Trump, in the Sept. 29 presidential debate, notably refused to state plainly that he’d accept election results and instead said he is “urging my supporters to go into the polls and watch very carefully, because that’s what has to happen. I am urging them to do it.”

At the same time, racial and social unrest over alleged incidents of police brutality against African Americans over the past year are stoking fears of BLM and Antifa voter intimidation.

Follow the exurbs and smaller cities.

Trump’s reelection depends on driving up his margins in rural areas and smaller towns and cities, those expansive swaths of red on the county-by-county results map from 2016.

But Biden is casting a wide demographic and geographic net. His ideal coalition is anchored in metro areas, but he hopes to improve Democratic turnout among nonwhite voters and college-educated voters across the map.

There are places where the competing strategies overlap: exurban counties — those communities on the edges of the large metropolitan footprints — and counties anchored by smaller stand-alone cities.