If either Donald Trump or Joe Biden is to win the presidency on Tuesday night (or, more likely, on the few days that follow), he will have to do it by taking some combination of the following six swing states: Florida, North Carolina, Michigan, Pennsylvania, Arizona, and Texas. Other states, like Wisconsin and Georgia, may come into play as the night proceeds, but these six battlegrounds represent the most crucial electoral votes on the path to 270.

And in each case, as the votes are being tallied on Election Day, there are individual counties that could give us an early indication of which way their state will swing once the final votes are tallied. Here is a look at the bellwether counties for the 2020 presidential race.

Sumter County, Florida: For Joe Biden, there is no more valuable prize than Florida. If he takes this state, the presidency is his, no matter what else happens on Tuesday night. And early returns from Sumter County, home to that sprawling retirement community known as The Villages, will almost certainly tell us if Biden has a realistic shot to win the Sunshine State. In 2016, Sumter went for Donald Trump by a huge margin over Hillary Clinton—68.8% to 29.5%—and it went solidly Republican in both 2008 and 2012. But many political forecasters, including Dave Wasserman of the Cook Political Report, are predicting a “gray revolt” for Biden, based largely on seniors’ concern over the coronavirus and their anger over the Trump administration’s bungled response to the pandemic. “Trump’s newly adopted home state of Florida is a must-win for his hopes of a second term,” Wasserman recently wrote. “But if the ‘gray revolt’ against him depicted in polls and dispatches from The Villages comes to pass, it should be apparent quickly on election night.’’ (Another county to watch: Pinellas, which backed Trump after twice voting for Barack Obama.)

Luzerne County, Pennsylvania: It’s no accident that both Donald Trump and Kamala Harris made campaign stops in Luzerne County, in northeastern Pennsylvania, on the final Monday before Election Day. This working-class county, not far from Biden’s childhood home of Scranton, is emblematic of the swing in the state populace that flipped Pennsylvania from blue to red in that last two elections. Barack Obama won Luzerne by five percentage points in 2012, but Trump took it by 19 in 2016. It’s expected to be a key battleground again this year, and should give a good indication of whether Biden can win back this part of Pennsylvania, and thus the state itself. (Another county to watch: Chester, a suburban Philadelphia county that went for Hillary Clinton in 2016 with 52.6% of the vote, and that Democrats hope will exceed that margin in 2020 with a large turnout of college-educated women.)

Kent County, Michigan: As we get closer to Election Day, Michigan seems an increasingly safe bet for the Biden campaign, thus reversing the nightmare of 2016, when Hillary Clinton lost the state by just shy of 11,000 votes. But if Biden wants to win Michigan, he almost certainly needs to carry Kent County. This county, the home of Gerald R. Ford and a place where the Republican establishment (including Education Secretary Betsy DeVos) still dominates the local political and economic scene, might seem an unlikely place to propel Joe Biden to victory. But in 2016, it went for Donald Trump by only 9,000 votes over Hillary Clinton, and then, in 2018, the Democratic candidate for governor, Gretchen Whitmer, won the county by four percentage points over her Republican rival. That Donald Trump seems to recognize the importance of holding onto Kent County is indicated by the fact that the president chose Grand Rapids, the county seat, for his final appearance on the 2020 campaign trail, giving a speech that seemed to sum up his divisive, corrosive reelection campaign. “I’ve fought for you harder than anyone has ever fought before,” Trump said during a speech given at midnight to a crowd gathered at the Gerald R. Ford International Airport. “Do you want to be represented by a politician who hates you?” (In terms of turnout, the key Democratic counties to watch are Genesee, home to Flint, and Wayne, home to Detroit. Joe Biden and Barack Obama made their only joint appearance of the 2020 campaign in those two cities on Saturday.)

Nash County, North Carolina: North Carolina has been a reliably red state in recent elections, with Republican nominees for the White House winning the state in 10 of the last 12 elections. Barack Obama took the state in 2008, but then lost it to Mitt Romney in 2012. In 2016, Donald Trump beat Hillary Clinton by 3.6 percentage points. But in 2020, the state is definitely up for grabs, though Trump probably needs it more than Biden if he is going to get to 270 electoral votes. “Most paths to the White House go through North Carolina,” Chris Cooper, professor of political science at Western Carolina University, recently told CBNC. “It’s particularly true for President Trump.” One key indicator of how the state might go is Nash County. This once-reliable Republican stronghold, which gave GOP candidates double-digit victories in 2000 and 2004, went for John McCain by just a margin of 1.3% in 2008, for Barack Obama by 0.9% in 2012, and for Trump by a razor-thin 0.2% in 2016. Democrats are hoping to flip it back for Biden in 2020. (Another county to watch: Union. The populous county, in suburban Charlotte, went strongly for Trump in 2016, after doing the same for Romney in 2012 and McCain in 2008. But recent polling shows that many local Republicans are disaffected with the Trump administration, particularly over his handling of the pandemic. This county may not go for Biden, but a narrow margin of victory for Trump would indicate that the president is in trouble with the state as a whole.)

Maricopa County, Arizona: Home to Phoenix and more than 60% of the state’s electorate, Maricopa is Arizona’s most important county and the one that will almost certainly determine which candidate will win the state’s 11 Electoral College votes. It went narrowly for Donald Trump in 2016 (and strongly backed John McCain in 2008 and Mitt Romney in 2012), but in 2018 it supported a Democrat, Kyrsten Sinema, for U.S. senator. Will the county’s changing demographics, which have been trending younger and more highly educated, tip the state to a Democratic president for the first time since 1996? Advance voting recently passed 2.4 million, and exit polls suggest that Democrats held the edge in that balloting. But local Republicans are hoping that strong day-of voting will go their way, and give the state to Trump once again. (Other counties to watch: none.)