The long history of American socialism has been built in left-wing strongholds. A century ago, Oklahoma and Wisconsin were Socialist Party bastions, while North Dakota and Montana were hotbeds of radical politics. And there was always Pennsylvania. From the 1910s through the 1940s, Socialist Party members served as state legislators, mayors, city councilors, and school-board members. The Pennsylvania party, with its deep roots in Reading, produced national Socialist leaders, including candidates for president and vice president. And after the party’s fortunes faded following World War II, a former Socialist from Reading, George Milton Rhodes, was elected to Congress as a Democrat and went on to serve for two decades as one of the US House’s steadiest supporters of organized labor and civil rights.

Rhodes finished his last term 50 years ago. So it has been a good long while since even the memory of socialism has been a factor in Pennsylvania politics.

But the dry spell is over. Socialists have been on an electoral winning streak in some parts of the country for a number of years—Socialist Alternative’s Kshama Sawant made her electoral breakthrough in 2013, winning a major race for the Seattle City Council—but the results from western Pennsylvania in the past two years have been particularly striking. And, now, national observers are starting to take note. “Democratic Socialists scores big wins in Pennsylvania,” declared CNN this week, while The New Yorker announced: “A Democratic-Socialist Landslide in Pennsylvania.”

Tuesday’s primary election in Pennsylvania saw young progressive women who were backed by Democratic Socialists of America winning Democratic primaries all over the place—in cities and suburbs, to the west and to the east. “We’re turning the state the right shade of red tonight,” declared Arielle Cohen, the co-chair of the Pittsburgh chapter of DSA

A pair of DSA-endorsed candidates for the Pennsylvania House of Representatives seats in the Pittsburgh area, Summer Lee and Sara Innamorato defeated veteran legislators in Democratic primaries. In the Philadelphia area, Philly DSA-backed candidates Elizabeth Fiedler and Kristin Seale also won hard-fought primaries for state House seats.

The wins by Lee and Innamorato were especially sweet, as the DSA-backed candidates upset members of a Pittsburgh-area political dynasty, cousins Paul and Dom Costa, whose stances on social and economic issues had frustrated progressives. “Last night’s victories were a monumental shift in the political landscape of Pennsylvania,” explained Cohen. “Our candidates won on popular demands that were deemed impossible. We won on health care for all, we won on free education.” WESA, the local NPR affiliate, reported that this spring’s southwestern Pennsylvania primaries saw “a wave of progressive Democrats challenging what they call the moderate establishment this election season. It echoes those throughout the country that have seen left-of-center political newcomers secure seats in state and federal government.”

Both Lee and Innamorato are expected to win easily in November, as no Republicans ran for the heavily Democratic seats.

The likelihood that they are headed for the legislature had Daniel Moraff, a Pittsburgh DSA member who was a campaign organizer for Lee, suggesting that the campaign had provided “a blueprint for how you can run a campaign on a radical platform and reach the demographics it needs to reach.”

“This is about lighting a fire and keeping that fire burning,” said Moraff.

In fact, Pittsburgh DSA began lighting fires last year in the region, when a pair of contenders who were backed by the group—district judge candidate Mik Pappas and County Council candidate Anita Prizio—beat incumbents to secure victories that the Pittsburgh Post-Gazette described as “the first notched by a local chapter of a fast-growing political national movement.”

Those victories came as DSA-backed candidates (some members of the group, some progressives who sought its endorsement) won 21 of 32 races they contested in 2017 —electing state and local officials from Moorhead, Minnesota, to Knoxville, Tennessee, to Billings, Montana. In the highest-profile 2017 victory, 30-year-old Lee Carter defeated the Republican majority whip of the Virginia House of Delegates to win a state legislative seat. But few states have seen so many wins by DSA-backed candidates as Pennsylvania, and few regions have seen so many breakthroughs as the Pittsburgh area.

DSA was not the only group backing Lee and Innamorato, both of whom were endorsed by Our Revolution, the national group formed by backers of Senator Bernie Sanders’s 2016 campaign for president as a democratic socialist, the proudly militant United Electrical Workers union, and groups such as Planned Parenthood and the Sierra Club.

But the support they received from the energetic young members of DSA was a major factor in both races. When she was asked about being backed by socialists, Lee answered with a question.

“I would ask, ‘How did capitalism work for you?’” Lee explained to CNN. “Because I can tell you in my community it’s not working. Capitalism works on the back of my community and communities of color and poor communities across this country. It was built that way and it is working exactly the way it is supposed to.”

The “s” word could come up this fall in the Philadelphia suburbs. Seale, a member of the Rose Tree Media School Board who was a Sanders delegate to the 2016 Democratic National Convention, is taking on Republican State Representative Chris Quinn in a competitive suburban district.

Elizabeth Fiedler, who won a hard-fought primary in an overwhelmingly Democratic South Philadelphia district, is likely to prevail in the fall. Indeed, her website announces: “Our movement is victorious. This is a movement with a groundswell of support from working people—this is what democracy should look like.”

That’s how DSA sees it. “A political revolution is coming,” says Tascha Van Auken, a co-chair of the group’s national election committee, “and establishment politicians can get on board or be swept away.”