A Donald Trump rally in Harrisburg, Pennsylvania, last week brought out a large and varied crowd: teens in business suits, Republican members of Congress, and racist skinheads.

Almost a dozen white men decked out in the regalia of a white supremacist group hung out toward the back of the Trump-loving crowd, cheering heartily at the mogul’s calls for stricter immigration enforcement, and eyeing police as they dispatched protesters.

The group is called Keystone United—also known as the Keystone State Skinheads—and it’s one of the better-organized state-level white supremacist franchises in the country.

Its members sport tattoos of Norse symbols and shiny black jackets with patches displaying their logo, a white pit bull, and the letters KSS. They have a lot of trouble with the law.

And they love Trump.

Without explicitly endorsing white supremacy, the Republican presidential frontrunner has used all the right buzzwords to attract white supremacists of every stripe. And his skinhead support is especially visible in Pennsylvania, which holds its presidential primary on April 26, as the state has a long, dark history of white supremacist organizing and intimidation. Much like Michigan, which Trump won last month by 12 points, Pennsylvania has incubated a special kind of Rust Belt racism.

Industrial decline in the state hasn’t just fed the economic depression that Trump promises to magically fix; it’s also fueled a white supremacist renaissance whose participants are primed to lap up the mogul’s calls for anti-Muslim discrimination and xenophobic immigration policies.

An investigator for the Anti-Defamation League, who asked us not to publish his name, said Keystone United members are regulars at Trump events around the state. They wear their regalia, don’t bother hiding their tattoos, and cheer right along with everyone else as Trump bashes immigrants and calls for revolution.

Since its founding in 2001, Keystone United chapters have sprung up around the state. The group sells White Lives Matter bumper stickers on its website, which show up on street signs and newspaper dispensers. The investigator added that of skinhead groups operating on a state-level, Keystone United is one of the best-organized in the country. The Terrorism Research and Analysis Consortium concurs, describing them as “a well-organized, well-established, and increasingly violent group.” And its website shows little subtlety as to their ideology. A recent post, for instance, bemoans Andrew Jackson’s removal from the front of the $20 bill.

“The fact that Harriet Tubman can take his place without protest, symbolizes the apathy that has replaced our will to power,” it reads.

There’s also tons of anxiety about the Jews.

Keystone United isn’t the only white supremacist group to ride the anti-immigrant wave which buoys Trump. The ADL investigator added that a newer organization has recently materialized in Pennsylvania, imported from Finland: a group called Soldiers of Odin, which seeks to patrol and intimidate immigrant communities—particularly Syrian refugees, many of whom have recently settled in Pennsylvania’s Lehigh Valley.

White supremacy as a political and economic force is a major part of Pennsylvania’s history. It became highly visible in the state during the Great Migration—when millions of African Americans moved from the South to the North and Midwest during the first two-thirds of the 20th century, many seeking Rust Belt factory jobs. James Peterson, the director of Africana Studies at Lehigh University, said many white workers didn’t want the competition, so they worked to intimidate them and shut them out. The Ku Klux Klan in particular was highly active in Western Pennsylvania in the 1920s, as scholar John Craig has detailed. (They likely would have loved Trump; former KKK Grand Dragon Scott Shepherd told The Daily Beast in March that Trump is “pretty much in line with their beliefs.”)

Meanwhile, prisons became a significant industry in the state. Philadelphia’s Eastern State Penitentiary, built in 1829, provided a model of solitary confinement that hundreds of other prisons followed, as NPR details. In central Pennsylvania, a host of prisons sprouted up over the 20th century, where disproportionate incarceration of black men produced jobs for predominantly white communities.

“Economic depression, with the rise of prison industrial complex, create quite fertile ground for white supremacist ideology in the 21st century,” Peterson said.

The Great Recession exacerbated those long-percolating racial resentments, he added. As factories closed and jobs vanished, white poverty and white supremacy grew in tandem.

“There’s often an underlying economic justification,” he said. “Keeping black folks out of unionized work in the steel and coal industries, diminishing the capacity of black folks and brown folks to vote and to have control over their municipal governments—white supremacy often has these underground or less visible economic attributes that now, as we look at the state of Pennsylvania, we can see.”

The state’s history of anti-black agitation and resentment of anyone who wasn’t white has produced pockets of some of the country’s most organized white supremacists.

And they’re eager to stump for Trump—and for everything he stands for.