Joe Biden and Mike Pence are visiting 4 key areas in Pennsylvania. Here’s why they’re so important.

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The presidential race will kick into split-screen intensity in Pennsylvania on Thursday.

Mike Pence and Joe Biden are both visiting the state on one of the busiest campaign days since the onset of the coronavirus pandemic. The current and former vice presidents are stopping in four regions with starkly different political characters that show why Pennsylvania is such a contested battleground.

Pence will hold one event in a Republican stronghold that voted heavily for Donald Trump in 2016, and another in a suburban Philadelphia county that has forcefully rejected him. He will also visit the deep-blue city — rallying with police officers in a section of Philadelphia where the Trump campaign thinks it can make inroads.

Biden, the presumptive Democratic nominee, will speak near his Scranton birthplace, in a region where Republicans have made significant gains.

Combined, the visits are pieces of a puzzle in which any shift, even a small one, could make a crucial difference in a state that was decided by about 44,000 votes in 2016, or less than 1% of the total — and which again could determine who wins the White House.

It all comes amid staggering unemployment, a worsening public health crisis, and turmoil over systemic racism. Public polls show Biden leading Trump by 5 to 10 percentage points in the state, though it’s early.

Pence will meet with business leaders in Chester County and then the police union in Philadelphia, touching on the major themes of Trump’s reelection campaign: his promise to revive the economy and his disdain for recent protests.

Biden, meanwhile, will head to Dunmore, just outside Scranton, where he will pitch his own vision for restoring prosperity in a place that has long felt left behind — by both the economy and, increasingly, by the Democratic Party.

Here’s what you need to know.

Lancaster County, where Pence will attend a fund-raiser, gave Trump his fourth-largest vote haul in 2016, after only Allegheny, Bucks, and Montgomery Counties.

It’s an area Trump and Pence have visited frequently, including a stop by the vice president on the day the Senate acquitted Trump of impeachment charges.

”The path to winning Pennsylvania starts with us right here in Lancaster County,” said Lancaster GOP Chairman Kirk Radanovic. “Over the past two weeks we have been handing out hundreds of Trump yard signs. People understand what is at stake.”

While Trump won Lancaster County by 20 points, the city of Lancaster and other parts of the county have started trending more Democratic. The county ranks ninth in the state in the number of registered Democrats, which shows opportunity for growth, said Diane Topakian, chair of the Lancaster County Democrats. “A voter can be ideologically Republican, but these two men are not representative of the Republican Party of 10 years ago,” she said. “We’re not going to see a 20-point turnout for Trump again.”

In many ways, the shock of the 2016 presidential election can be traced to places like Lackawanna County in Northeast Pennsylvania: a traditional Democratic region that broke dramatically toward Trump. Between there and neighboring Luzerne County, Trump scored a 55,000-vote swing from the 2012 presidential race.

Biden’s appeal to such white, working-class areas was one factor many Democratic voters weighed when choosing him as their nominee.

He’ll arrive in the county as Democrats see an opening: They believe Trump’s mishandling of the coronavirus betrayed the trust voters put in him.

Jean Harris, a political scientist at the University of Scranton, said voters are evaluating Trump differently since the pandemic.

“People are being more critical than last time,” Harris said. “Because we’ve now seen him in action, people can ask different questions, people have a different understanding of who he is.”

It also helps, Harris said, that “people don’t dislike Biden like they disliked Clinton.”

But recent registration numbers suggest Democrats are still losing ground: Their registration edge in Lackawanna and Luzerne has fallen to its lowest level in two decades, according to The Citizens’ Voice.

“Literally, I don’t know anyone that supported President Trump in 2016 that is not supporting him this time,” said Lance Stange, the Lackawanna County Republican chairman.

He downplayed Biden’s chances of reversing Democrats’ decline in the region.

“The guy’s been in Washington longer than I’ve been alive,” said Stange, born in 1976, three years after Biden came to the Senate. “We’re supposed to believe that if we just give him another four years in Washington he’ll help us this time?”

Ed Mitchell, a Democratic consultant, said Northeast Pennsylvania is undergoing a shift similar to the one that has turned the state’s Southwest into deep-red territory. But given Biden’s hometown roots, he also argued that the region could be close.

“There are people around here who are thinking twice about [Trump],” Mitchell said. “It’s going to be tough here, but it’s not impossible.”

Chester County was once a Republican stronghold, riding an economy so powerful that businesses were struggling to find workers. But the political atmosphere and economy have seen stunning shifts. Each could have huge implications for Trump.

“When we sat down in February, the biggest issue in Chester County was the fact that the unemployment rate was 3%,” said Guy Ciarrocchi, president and CEO of the Chester County Chamber of Business and Industry. Now, Chester County has an unemployment rate around 10%. “Which is something most businesspeople haven’t seen in our lifetime,” he said.

Ciarrocchi will be among the local business officials who sit with Pence for a roundtable at Rajant Corp. in Malvern.

“We’re looking for guidance of what comes next. … What’s the regrowth plan?” Ciarrocchi said. “What does the administration really think that timeline is? Is it months? Is it years?”

Trump, who had planned to build his reelection around a strong economy, now argues that he is the leader to bring the economy back.

Even when jobs were plentiful, though, Chester County was turning against the GOP. The county saw a 26,000-vote swing toward Democrats in 2016 and the party has continued to gain in elections since.

State Rep. Christina Sappey is one of a number of Democrats, often women, who have won seats previously held by the GOP since Trump’s election. She said Trump’s handling of the pandemic is the overwhelming focus in her community.

“People are very concerned that nationwide our numbers are not going in the right direction and that at the highest level our leaders are not listening,” she said.

Pence is a better ambassador than Trump for undecided voters in a place like the Philadelphia suburbs, though, said Charlie Gerow, a GOP consultant in the state.

“His style, his demeanor, his message all connect with suburban Philadelphians,” Gerow said.

Philadelphia’s 1.1 million registered voters are 12% of the state’s electorate. The number of votes either candidate can pull out of the reliably Democratic city will matter.

Hillary Clinton won Philadelphia decisively but captured about 4,000 fewer votes than President Barack Obama did in 2012. Trump picked up 12,000 more votes than Mitt Romney received in 2012. Most of those Republican votes came from the Northeast, where Pence will meet with police on Thursday.

“This is all about trying to squeeze as much water out of a rock as possible,” said Mike Mikus, a Democratic operative based in Pittsburgh.

The Northeast neighborhoods have tilted more Republican, said Dan Lodise, a Democratic operative who managed an unsuccessful campaign against longtime Republican City Councilman Brian O’Neill.

Lodise said he’s seen worrisome signs for Democrats. ”It’s one of those stories I don’t think enough people talk about,” Lodise said. He said Trump energized Republican voters in the Northeast and created new ones.

“You see a lot of 25- to 65-year-old white working-class men who shifted,” Lodise said. “They not only voted for Trump but have continued to vote for Republicans since.”

He noted that U.S. Rep. Brendan Boyle and Gov. Tom Wolf were reelected in 2018 by much slimmer margins. Both dipped about six points from four years prior.

“I’ve been doing this work in this community for 16 years,” Lodise said. “I’m legitimately concerned.”