On hot summer nights in Willow Grove, a young Jill Biden would sneak out of her house after her parents fell asleep and break into the Upper Moreland Swim Club. It was the summer destination for families in the Philadelphia suburb. But her family couldn’t afford a membership.

So the potential future first lady of the United States would meet a friend in the dead of night, dodge speeding cars to cross the Pennsylvania Turnpike, and climb over the fence for a midnight swim.

“I can’t even believe that I did it,” said Biden, 69. She didn’t tell her mother about the escapes for “a long, long time.”

Biden reminisced about her Philadelphia roots during an interview last month in the courtyard of the Betsy Ross House. Behind her, affixed to the brick building believed to have housed the nation’s most famous Revolutionary seamstress, a little black heart read “Little Rebel.”

It’s an homage to Betsy Ross’ nickname. But it also could have described Biden as a girl growing up, first in South Jersey and then the Philadelphia suburbs.

“I was kind of rebellious,” Biden said. “I loved to pull pranks and I would sneak out of school and run up to the hoagie shop that was on the corner, those kind of things — innocent things.”

Then there was the time she dealt with a neighborhood bully who had been terrorizing her younger sister by knocking on his door and punching him in the face. Her dad gave her an “atta girl” for that one. Decades later, as Joe Biden celebrated a political comeback in the 2020 Democratic presidential primaries with a campaign rally in Los Angeles, Jill Biden straight-armed a charging protester to protect her husband.

Asked about the encounter then, she shrugged:

“I’m a good Philly girl.”

For all the years Jill Biden has lived in Delaware, she points to the cradle of the American Revolution as the place she learned about empathy, independence, and resilience. Her upbringing here prepared her, she says, for a life marred by tragedy, elevated by opportunity, and now a campaign in which, as a reluctant political participant herself, she has become a highly visible campaigner for her husband.

“Philadelphians are really resilient. It’s a city with a lot of grit, and I love that,” Biden said.

“My parents truly gave me a gift, in that we were raised ... in a household where there was just so much love and support,” she added. “They made us feel so safe and secure and I really think that had an influence on my life. ... They really grounded me in who I was and gave me confidence.”

Jill Tracy Jacobs was born in Hammonton, in Atlantic County. Her father, Donald Jacobs, a former World War II Navy signalman, was a bank teller and worked his way up to president of a Chestnut Hill bank. Donald Jacobs was raised in a working-class Italian family. He went to business school in Philadelphia through the GI Bill and met Bonny Jean Godfrey while ordering ice cream at her family’s pharmacy, a Rexall drugstore in Camden.

They had three daughters — Jill, Jan, and Bonny — then twins Kim and Kelly 10 years later. The three older girls shared a bedroom in Hatboro before the family moved to Willow Grove, the Montgomery County town where Jill Biden spent most of her childhood.

Willow Grove in the late 1960s was known for the amusement park that later became a mall and for small-town events like homecoming football games and fund-raisers for the local hospital. “Life’s a Lark at Willow Grove Park,” went a jingle for the amusement park. It all contributed to what Biden described as a kind of Leave It to Beaver upbringing.

“She took care of me. She was there if I needed her.”

Winters were spent sledding with neighborhood kids or skating on frozen canals in Yardley. Summers meant watching Phillies games with her dad on a black-and-white Philco. She waitressed down the Shore in Ocean City.

Every Sunday, the family would ride from Willow Grove to Hammonton for dinners with both sets of grandparents. They would drive through Philadelphia, passing rowhouses and the Nabisco factory before crossing over the Tacony-Palmyra Bridge, Biden wrote in her 2019 memoir.

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Her sister Bonny Jacobs — the one whose bully Biden punched — said Jill, as the older sister, was the leader of the pack.

“She took care of me. She was there if I needed her,” Jacobs said. “As she got older, I watched everything she did — she put on makeup and when she would leave I’d try her makeup on.”

Later, Biden helped her younger sister with college applications and moved her into her dorm at the University of Delaware. Jacobs is now a flight attendant who lives in Kennett Square, 10 minutes from their sister Kim. Jan lives in Ocean City. Kelly lives near Willow Grove.

“The four of us are amazed, like, gee, our sister could be first lady,” Jacobs said. “But ... first lady is a natural transition for her.”

At Upper Moreland High School, Biden was a good student, pretty, popular, and very involved in school activities, friend and classmate Liz Leonard recalled.

“She was always willing to help with our whole class,” said Leonard, who was class president and still plans reunions for the Class of 1969. “Everyone is just so excited for her. And it’s not political. We’re just generally happy for her.”

A “Philly for Jilly” fan club, including some Upper Moreland High School alumni, has been helping the Biden campaign.

One of the last times Leonard saw Biden was at Biden’s mother’s funeral in 2008. As soon as they saw each other, Biden pulled her in for a long, teary embrace.

“Her mother really was a wonderful guide and mother for them and set a wonderful example that I think Jill has followed all her life,” Leonard said.

As Biden put it last month at the Betsy Ross House: “I always felt that I had her strength in me.”

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Biden went to Brandywine (now Widener University) for her first year of college. She transferred to the University of Delaware and at 18 married Bill Stevenson, who played football at the school. Their marriage ended five years later. In her memoir, Biden recalled worrying at the time that she may never find the love her parents had. “I let go of fairy-tale endings,” she wrote.

But in March 1975, she and Joe Biden had their first date — in Philadelphia. She was a 24-year-old senior in college and uninterested in politics. Biden was a freshman senator, whose wife and daughter had been killed in a car accident two years earlier.

They went to see a movie, then to dinner, where conversation flowed better than she expected.

“It was kind of a blind date that we went out on and I didn’t think I’d really — I thought, ‘OK, I’ll go out with him once and that’ll be it,’ ” she recalled. “I just didn’t think he would appeal to me.”

Their courtship is one of Joe Biden’s go-to stories on the campaign trail. Two years and five proposals later, they got married. It took that many asks, Jill Biden said, because she wanted to be sure that, at 25 and in the beginning of her career, she was ready to become a wife and mother of two for Biden’s sons, Hunter and Beau.

“She put us back together,” Joe Biden said in a video about Jill that aired during the Democratic National Convention in August. “She gave me back my life. She gave us back a family.”

Philadelphia remained a date-night destination for the Bidens, who often came up from Wilmington for dinner in the Italian Market or Center City when Beau and daughter Ashley went to the University of Pennsylvania. Ashley still lives in the city. Beau, the former attorney general of Delaware, died of brain cancer in 2015 at age 46.

When Jill Biden talks about Philadelphia, she can sound like a tourism ad as she rattles off her favorite local spots: Dante & Luigi’s Italian restaurant, the Franklin Institute, Kelly Drive for runs. She took up running in her late 40s to manage stress and has run in several Broad Street races and the Philadelphia half marathon.

“I get such a sense of peace and balance,” she said. “Any time a negative thought comes into my mind I just push it out.”

She has master’s degrees from West Chester University and Villanova University, and a doctoral degree from the University of Delaware. She spent most of her career teaching at community colleges because she likes working with students who are often taking a second shot at school or starting a new career.

“I could see how I could change their lives,” Biden said. “I could help guide them and direct them and give them confidence.”

Biden plans to continue working full time as a community college professor if her husband wins the election. She would be the first first lady to have a separate job while in the White House. She’d also make community colleges a part of her own agenda, along with cancer research and help for military families.

Mary Doody interviewed Biden when she applied to work at Delaware Technical Community College in the early 1990s. “You could just tell she was a really good teacher,” Doody said. “She just has a kind of presence about her that I felt like students would be drawn to, and she was funny. If you’re going to be in a classroom, you have to have a sense of humor.”

Doody once walked into her cubicle at Delaware Tech to find an enormous 50-pound pumpkin sitting at her desk with a face scrawled on it, a prank gift. Jill Biden is known for her pranks, once hiding in the overhead bin of Air Force Two to surprise Joe when he came aboard. She learned that playfulness from her parents, she said.

“Their marriage was ... strong and loving and full of laughter,” Biden said.

Doody and Biden still connect over gardening, cooking, and books. “She’ll text me, ‘I need a book!’ ” Doody said. “And I’ll say, ‘How can you have time?’ ”

After her husband became vice president in 2009, she continued teaching at Northern Virginia Community College but kept a low profile. She went by “Dr. B,” and Secret Service agents dressed like college students to blend in — so successfully that some students had no idea their professor was the second lady. She defended her dissertation on student retention in community colleges using her maiden name.

“She wanted to not be identified as being someone’s wife,” Doody said. “She’s ‘Dr. B.’ ... And I think that’s just so important to her. She says all the time, ‘Teaching is who I am.’”

Biden has said she hated the term second lady — preferring captain of the vice squad.

At a virtual campaign fund-raiser in September, she told several spouses of elected officials: “You are leaders in your states, advisers, advocates, friends, confidants. And so much more than ‘lovely wives.’ Didn’t you just hate it when people called us that?”

Annie Coons, who is married to Delaware Sen. Chris Coons, a top Biden supporter, said she has always admired Jill Biden’s independence.

“You have to have your own identity,” Coons said of Biden’s philosophy of life as a politician’s wife. “You have to believe in yourself first. ... Don’t give up yourself — be who you are.”

“She’s never been a political person,” Coons added. “But she’s become such a strong and powerful voice for Joe and the campaign.”

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As Chris Coons put it: “Jill is someone who has a big heart. She’s a tough Philly girl, but she’s also gracious. To be blunt, one of the ways ... I gauge my colleagues is their spouses, and particularly with men ... I am closest to and most admire senators whose spouses are strong-willed, capable, independent people.”

On the campaign trail, Biden is energetic and almost omnipresent, sometimes doing in-person or Zoom events dawn to dusk. Behind the scenes, she’s one of her husband’s closest confidantes, often helping direct him — including physically yanking him away from people if he’s too close for COVID-comfort.

“I’ve gotten used to it,” she told The Inquirer of politics. “It is my life now.”

Biden touts her Philadelphia ties any chance she gets — which is a lot, given her frequent visits to Pennsylvania. She says her middle-class upbringing is something she and Joe Biden, a native of Scranton, bonded over early.

“In my English classes we talk a lot about the power of stories and how they can shape our identities,” she told a crowd in Johnstown earlier this month, before recounting her own family’s start as Italian immigrants and her husband’s family’s start as Irish immigrants, just a few hours away in Scranton.

“As kind and thoughtful and empathetic as she can be, she’s no pushover. She’s not exactly a shrinking violet.”

“In so many ways this election is about those stories and how to make sure every family in America has the same opportunities that Joe and I had,” she said.

In Western Pennsylvania, she referred to the state’s fierce regional disagreements over convenience stores (Wawa in the east, Sheetz in the west) and football teams. She quickly turned that into a pitch for how her husband can unite Eagles and Steelers fans alike. She’s particularly engaged when she’s talking to teachers or students.

She wore an Eagles shirt to a fund-raiser with Cowboys Hall of Famer Emmitt Smith and dyed a streak of her hair purple for a chat with purple-haired soccer star Megan Rapinoe. The Flyers are Biden’s first love, but she follows all Philadelphia sports teams, often asking staffers when the Eagles are playing so she can follow the score between campaign events.

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But this has also been a uniquely acrimonious race for Jill Biden.

She is sometimes asked several times a day to defend her 77-year-old husband’s mental fitness for office, which Donald Trump and his allies question often. Her son Hunter has been maligned by Trump. She tries not to take it personally. “I think Donald Trump’s just looking for anything to cause a distraction,” she told The Inquirer.

When CNN’s Jake Tapper, a Philadelphia-area native himself, asked Biden last month about her husband’s well-known propensity for verbal gaffes, she cut in and objected to the premise. “You can’t even go there. ... You cannot even say the word gaffe,” she said.

“As kind and thoughtful and empathetic as she can be, she’s no pushover,” said friend and former Delaware Tech colleague Charlotte Brainard. “She’s not exactly a shrinking violet. She can be tough — and she never lost her accent.”

Brainard also sees a kind of symmetry in the tragedy the Bidens have endured and the plight of a pandemic-stricken nation today. She recalled Biden’s kindness when her father was dying — the phone check-ins and the food basket from her favorite Italian restaurant in Delaware.

In fact, almost everyone interviewed for this article had a story about some unexpected act of kindness from Jill Biden when someone was sick or died.

“She is one of the most grounded, decent human people I’ve ever met,” said former Delaware Gov. Jack Markell, who led a memorial service for Beau Biden in 2015.

Brainard said it felt as if the entire state of Delaware attended that memorial.

“People had waited hours in line, and you know what? They waited and they greeted every single person in line and that just goes to show how strong she is,” Brainard said. “At the worst possible time of your life to hang in there and greet everyone.”

» READ MORE: ‘That girl from Philly’ Jill Biden says her husband Joe can heal America

Earlier this month, Biden talked with female party leaders at a backyard gathering in Swarthmore. She reflected on how she and Joe Biden have supported each other through the years. When the kids were younger, he would come home from Washington on Amtrak every night to put them to bed, while she studied for graduate school at Villanova at the kitchen table.

Healing a family shattered by grief, she told the women, is similar to making a divided country whole again.

“We found that love holds a family together,” she said. “Love makes us flexible and resilient. And though it can’t protect us from the sorrows of life, it gives us a refuge, a home.”