Jamie Gauthier’s primary victory over longtime Councilwoman Jannie Blackwell wasn’t just an upset.

It was an earthquake, caused by tectonic demographic shifts that could reshape city politics in the years to come.

West Philadelphia’s 3rd Council District, shaped by gentrification, created a changing electorate with fewer ties to the politics of the past. The more an area within it had changed in recent years, the more likely it was to vote for Gauthier, according to a detailed Inquirer analysis of precinct data, the most granular level at which election results are available.

Gauthier won by 12 percentage points over the seven-term incumbent in the May 21 primary. She did best in younger and more affluent sections of the district, drawing voters who have also supported other antiestablishment candidates.

The analysis also showed:

  • The better-educated the precinct, the more likely it was to vote for Gauthier. She won 80 percent of the vote in areas where a majority of adults have a bachelor’s degree or higher, while Blackwell won 55 percent of the vote in areas where fewer than 1 in 5 adults have a bachelor’s degree.

  • The higher a precinct’s home values, the more likely it was to vote for Gauthier. She won 79 percent of the vote in areas with a median home value above $200,000; Blackwell won 54 percent of the vote in areas with a median home value below $100,000.

  • Precincts with more longtime registered voters were more likely to support Blackwell, while areas with newer voters supported Gauthier.

  • The younger the precinct, the more it voted for Gauthier; in precincts Gauthier won, the average age of active voters was 41.8, vs. 48.5 in precincts Blackwell won.

  • Precincts that voted for Gauthier also tended to vote for Rochelle Bilal, who unseated two-term incumbent Sheriff Jewell Williams. And the more a precinct voted for Gauthier, the more it had voted for Larry Krasner in the 2017 Democratic primary.

Demographics of Gauthier's 3rd District Win

In the Democratic primary for the 3rd Council District, challenger Jamie Gauthier defeated longtime incumbent Jannie Blackwell by dominating in precincts with more expensive homes, higher incomes, and a high percentage of college graduates.

Click on the map for more information.

SOURCES: Philadelphia City Commissioners; Esri Demographics

Of course, messaging and candidates matter, too. Gauthier also connected with voters on issues facing the district and ran a more robust campaign than Blackwell, who was unaccustomed to facing a credible challenger.

But without that base formed by demographics, development, and dissatisfaction, Gauthier likely wouldn’t have stood a chance.

“Ten years ago to 20 years ago, the demographics of the district would have been much tougher for a challenger,” said Neil Oxman, the Democratic political consultant and president of the Philadelphia-based national media firm the Campaign Group. But things have changed, he said. “All you have to do is drive down Chester and Baltimore Avenues to see it — that gave something of a base that wasn’t there.”

Changing neighborhoods, changing voters

Blackwell has represented West Philadelphia for 27 years, taking over for her husband, who held the seat for 18 years before that. While its Council representative hasn’t changed, the Third District has, with 6 percent population growth over the last decade and brisk development in neighborhoods west and southwest of University City and along the Schuylkill waterfront.

Even neighborhoods seen as further behind in development, like long-impoverished Mantua, have seen glimpses of gentrification. Gauthier did well there, where there also is a large concentration of university students.

The district as a whole has gotten younger — 35 percent of residents are millennials, compared with the 24 percent who are baby boomers or older.

“The basic story of the University City revitalization is the outward expansion of the core institutions of Penn and Drexel,” said Kevin Gillen, senior research fellow at the Lindy Institute for Urban Innovation at Drexel University. That’s occurred over two decades and pushed deeper to the west and to the south, he said, while “the northern part has lagged somewhat.”

That matches the political preferences of the voters as seen in votes for Gauthier and Blackwell.

“There is something to a new generation of voters and creating some level of agency for themselves and their community,” said Erica Attwood, a lifelong West Philadelphia resident who chaired Gauthier’s campaign.

She added, though, that a part of Gauthier’s win “wasn’t just younger voters, it’s the more established voters, the black voters in the district who I think were fatigued.”

Indeed, even in areas Gauthier lost, she drew enough votes to keep Blackwell’s margin down, ultimately carrying her across the finish line: Gauthier got an average 65.9 percent of the vote in precincts she won, as well as 40.8 percent in those Blackwell carried.

An urban planner who formerly headed the Fairmount Park Conservancy, Gauthier has said she saw the race as a passing of the baton from one generation to the next.

She largely ran on the issues that come along with those changes, including protections for renters (she’s a renter herself), reducing or eliminating the 10-year tax abatement, and curbing the exclusive power council members have over land deals. She pitched herself as able to combat the negative effects of gentrification in the district, while also appealing — overwhelmingly — to its gentrifiers.

Blackwell, a longtime champion of the homeless and the poor, did less to carry her message to voters, new and old. She also was slow to raise money.

“Councilwoman Blackwell had a story to tell that could have appealed to the changing district,” said State Sen. Vincent Hughes, whose district includes portions of West Philly and who endorsed her. He believes the new voters wouldn’t have rejected Blackwell out of hand.

“They, however, don’t have the full history — and therein lies the problem,” he said. "You don’t tell them the story, they’re never going to hear it. … What student is not going to vote for someone who fights for low-income people on a daily basis? I think that’s a compelling story and a compelling message, but they’ve got to hear it.”

He also cited an “engaged digital and multimedia program” by Gauthier’s campaign, something Blackwell didn’t match. On the digital side, Blackwell didn’t even have a campaign website.

But, like the district, Gauthier’s campaign was a mix of old and new, combining digital ads and street teams knocking on doors.

She also benefited from the political action committee Philadelphia 3.0, which spent at least $300,000 in the three weeks before the election on mailers, field organizers, and digital advertising. Josh Kopelman, a venture capitalist who is also chairman of the board of the Philadelphia Inquirer, is a primary funder of Philadelphia 3.0. The PAC did not coordinate with the campaign.

“There’s nothing sexy to this,” said Trevor Maloney, Gauthier’s campaign manager. He said the campaign targeted people who voted in recent primaries and those who became politically engaged after President Donald Trump’s election.

“Every campaign worth its salt is going to pull a likely voter universe, and that’s what we did,” Maloney said. “I genuinely think this is all based on Trump’s election. The surge voters tend to skew younger. They are generally higher educated than the average citizen, and generally more affluent. We’re seeing this across the country, so it’s no surprise we’d see it here as well.”

Residents received upward of 20 mailers from Gauthier’s campaign or from Philadelphia 3.0 in support of her, while Blackwell sent out just a handful — in the final days.

Gauthier "had a hell of a promotion [effort],” said De’Wayne Drummond, president of the Civic Association in Mantua, which Gautier won. “You’re getting stuff in your door. You’d see stuff go up on poles, which I hadn’t seen since the early ’90s when I was 12 years old,” Drummond said. “I think the whole marketing piece and the whole internet piece made a difference.”

Implications for a changing city

Other insurgent candidates have assembled the same coalition as Gauthier did in the district, such as Bilal and Krasner.

Gentrification has been happening in West Philadelphia for years — “For University City, it’s a fairly mature process already,” Gillen said — and other sections of the city are in the throes of the process. It’s possible, political strategists and analysts say, that eventually new voter coalitions will form in other neighborhoods, driving political change in a city that has had a stable — or stale, depending on the view — political leadership class.

It also seems likely that the issues and concerns surrounding change will become even more prominent in the ongoing political debate over the city’s future.

For instance, in South Philadelphia’s 2nd District, the primary campaign conversation was also about development and how to balance neighborhood improvements with keeping people in their homes.

The demographics of neighborhoods that overwhelmingly backed Gauthier match those of the neighborhoods that voted for Lauren Vidas, a candidate running against Councilman Kenyatta Johnson in the district.

The races differed in many ways — Johnson ran a strong and well-funded campaign and more effectively communicated with voters than Blackwell did, ultimately winning reelection by 20 points. But some of the precinct-level demographic divides are the same and reflect the broader trend: As the city changes, its voter base will, too.

And the right candidate, the right campaign, can capitalize on it, said State Sen. Anthony Hardy Williams, who represents West Philadelphia and endorsed Blackwell.

“But you still have to have all the tools in place — a message and a candidate that represents that,” he said.

Staff writer Andrew Seidman contributed to this article.