After all, Biden’s home, to which he is expected to return when he retires from the White House on Jan. 20, 2025, after a single term, is less than 15 miles away, just south of the Delaware state line. Similarly, many Biden neighbors in the leafy Chateau Country estates north of Wilmington, Delaware, find the Chester County, Pennsylvania, borough of Kennett Square, with a population of just over 6,100 people, a convenient spot to shop, eat out, and take care of other daily activities.

There’s nothing unusual about such cross-state traffic. Think New York–New Jersey or Maryland-Virginia, plus Washington, D.C. But Biden’s familiarity in this corner of southeast Pennsylvania has possibly profound political implications for the 2024 presidential race.

Pennsylvania is the nation’s premier swing state in the neck-and-neck race between Biden’s chosen successor, Vice President Kamala Harris, and her Republican rival, former President Donald Trump. Both sides must win the Keystone State to have a realistic shot of winning a majority of 270 electoral votes. Both nominees have practically camped out in Pennsylvania ahead of Election Day, Nov. 5, and their campaigns are spending tens of millions of dollars each in the state of 13 million people.

Delaware, by contrast, is reliably Democratic in presidential politics. And anyway, it only has three electoral votes. But since Biden’s hometown area popularity stretches north, Biden’s status as a practical local just across the Pennsylvania state line, in Chester County, is a conspicuous electoral hole that Harris will have to fill.

The good news for Harris’s campaign is that Chester County is brimming with the sorts of well-educated, relatively high-earning voters now crucial to the Democratic coalition. In Chester County, the median household income is $104,000, per the 2020 census, which was the highest of all of Pennsylvania’s 67 counties.

Third senator from Pennsylvania

Yet it will be hard for the Harris campaign, in a matter of weeks, to equal the time Biden has spent in Chester County over the years, through his 1973-2009 Senate career and even as vice president for eight years during former President Barack Obama’s administration, when Biden frequently went home to Delaware.

Biden has continued his regular Delaware visits as president. And when Biden was seeking reelection before quitting the race after his weak June 27 debate performance against Trump, he appeared in Chester County several times.

Biden’s team knew of the political payoff there. The county delivered for him big time in 2020. Chester County provided Biden the largest percentage gain of any county in Pennsylvania over former Secretary of State Hillary Clinton, the losing 2016 Democratic nominee against Trump. Four years later, Biden won by nearly 54,000 votes, a victory of more than 17 percentage points. Biden won Pennsylvania over Trump by over 80,000 votes out of nearly 7 million cast, 50.01% to 48.84%.

Biden’s Chester County improvement helped offset losses in other parts of Pennsylvania previously considered reliably Democratic, such as in majority-Latino neighborhoods in Philadelphia — in two wards there, Biden performed worse than Clinton in 2016. In some other areas, too, voters increasingly cast ballots for Trump. Elsewhere, Democratic vote totals declined because turnout did — fewer people showing up in blue strongholds was effectively a gain for Republicans.

Pennsylvania has long been a state targeted by Democrats and Republicans alike, with competitive contests at almost every level of government. In the 2020 presidential race — four years after it helped send Trump to the White House by giving him about a 44,000-vote victory — both parties lavished attention on the Keystone State. Two years after Biden prevailed there, the GOP lost high-profile contests for governor and Senate, with the latter race producing the only Senate seat that year to flip between the parties.

Still, the combination of votes from Philadelphia, its collar suburbs, and Pittsburgh’s Allegheny County does not provide the Democrats with enough cushion to win the state comfortably in a presidential race. Democrats, as Harris’s campaign knows well, also need to do well in other, far-flung parts of the state that have been consistently moving in the Republicans’ direction.

In such a political game of inches, each voting corner of the state counts. Biden’s mantra that he was a “third senator from Pennsylvania” holds truer in Chester County than in the northeastern part of the state he usually cites.

Biden was born in Scranton, Pennsylvania, and was the first of four children of a car dealership manager with an up-and-down business career. Yet the family moved to Delaware in 1953 when he was 10. Biden has kept his attachment to Scranton throughout his long political career. However, vote totals from the area in his winning two vice presidential bids and successful 2020 run for president did not show an appreciable increase in Biden support in the Scranton area.

In marked contrast, Chester County is practically home to Biden. But very much not for Harris, his vice president and replacement nominee. To the degree the Harris campaign wants to deploy Biden on the campaign trail in the presidential fight’s final weeks, it likely will be in his political backyard.