The Feb. 3, 2023 incident was marked by apocalyptic images of black smoke billowing from rail cars, led to thousands of people being evacuated from their homes and prompted widespread fears about lingering health effects. Federal authorities almost immediately launched an investigation and sent environmental experts to Ohio, but Vance and other Republicans pilloried the Biden administration for what they saw as a lackluster response to a crisis in a part of the country where Democrats are scarce.

“The residents of East Palestine are not the type of people who elicit the sympathy of the bicoastal elite: They’re too white, too rural, and too conservative,” Vance said at a Senate hearing in the aftermath. The Ohio senator had already introduced legislation to improve railroad safety, predicting the industry would “demagogue” against it.

The derailment has taken on new significance after Vance’s selection as Trump’s running mate. The senator joined Trump when he visited East Palestine, eclipsing Biden administration officials in a moment the Trump campaign now credits with refocusing his election bid after a rocky start.

Vance and Trump spent much of the day side by side before the national news media, cementing their relationship. Highlighting the importance of the episode, on Wednesday night East Palestine’s mayor is scheduled to address the Republican National Convention ahead of Vance’s headline speech as the party’s vice presidential nominee.

Vance’s selection as Trump’s running mate solidifies the role of economic populism in a Republican Party that for years was dominated by business interests. Vance has called for policies that would boost wages for American workers, and in his brief Senate tenure he has praised the Biden administration’s efforts to battle monopolies, has sought to rein in big banks and championed rail safety legislation.

David Cohen, a political science professor at the University of Akron, said East Palestine provided Vance the opportunity to show off his approach. While Biden misunderstood people’s desire to see his leadership, Cohen said Vance readily sized up the moment.

“This showed that he wasn’t just going to be a senator that collected a paycheck and was simply worried about burnishing his credentials on social media,” Cohen said. “The train derailment was right up his alley. He is a populist and this was a fantastic populist issue.”

Unlike many transportation disasters, the derailment in East Palestine did not immediately capture national headlines before fading in significance. Instead, once officials made the decision to blow holes in tank cars they thought were at risk of exploding, thick smoke spewed above the community as hazardous chemicals burned. The images spread on social media, eliciting comparisons to the Chernobyl nuclear disaster. Tucker Carlson, then an influential Fox News host, picked up the story.

Vance positioned himself as an advocate for a community he argued would otherwise have been overlooked, telling news site Axios that he, Carlson and Trump had come to the realization that: “These are sort of our people.”

East Palestine is a town of fewer than 5,000 residents near the Ohio-Pennsylvania border. It is part of Columbiana County, where more than 70 percent of voters backed Trump in 2020.

County Commissioner Roy Paparodis (R) said Vance’s work in the aftermath of the derailment reflected his authenticity and helped ease people’s fears.

“When that event happened, the emotions and the anxiety around that was very high,” Paparodis said. “I thought he handled things extremely well. His words helped calm and make everyone feel better that we would have a positive outcome.”

Almost two weeks after the derailment, Vance posted a video of himself in jeans and a crisp white shirt investigating the state of a creek, where he said he could see dead fish and worms and a chemical sheen on the water.

“The fact that these chemicals are still seeping in the ground is an insult to the people who live in East Palestine,” Vance said. “Do not forget these people.”

At the time, Biden administration officials pointed to the steps they had taken to respond. National Transportation Safety Board investigators were on the scene within hours of the derailment, joined by the Federal Railroad Administration and the Environmental Protection Agency. They argued that sending senior federal leaders could have drawn resources away from the immediate response, although Transportation Secretary Pete Buttigieg ultimately visited East Palestine the day after Trump. (Biden visited this year.)

Officials cast their efforts as a textbook response to a safety incident that hadn’t caused any fatalities and Republicans were not universal in condemning the administration. A spokesman for Gov. Mike DeWine said last February that federal agencies provided what was needed and that the White House regularly communicated with the governor.

But some in East Palestine said their approach felt very different. As the derailment cleanup continued, Biden made a trip to Kyiv in support of Ukraine’s war against Russia. Trent Conaway, the town’s mayor, told Fox it was a “slap in the face.”

“That tells you right now, he doesn’t care about us,” Conaway said. He did not respond to interview requests Tuesday ahead of his convention appearance.

Democrats sought to highlight efforts by the Trump administration to weaken railroad safety standards. Project 2025, the blueprint for a Republican presidency compiled by the Heritage Foundation, calls for further regulatory rollbacks.

But Vance has largely been able to immunize himself from that line of criticism. In Washington, he formed an alliance with his Democratic counterpart Sen. Sherrod Brown, who himself has a populist streak, to pursue railroad safety legislation. The bill advanced ideas typically championed by labor unions and Democrats, a sign of Vance’s willingness to break with Republican orthodoxy when it comes to big business. They included standards for detectors designed to catch the kind of overheating wheel bearing that caused the derailment, rules for sharing information on hazardous chemicals with emergency responders, and minimum crews of two people on trains.

Greg Hynes, the legislative director for SMART-TD, a rail labor union, said Vance pushed harder than anyone for the safety legislation. “He was really making a valiant effort at pushing the bill forward,” Hynes said. “We have never had such a staunch an ally in a Republican senator in my time in D, C.”

Railroads lobbied against some of the key provisions in the bill. Jessica Kahanek, a spokeswoman for the Association of American Railroads, said the organization had spoken with lawmakers, including Vance, about “how rail safety legislation should both meaningfully improve safety outcomes and mitigate against unintended consequences.”

Yet, the bill has shown the limits of Vance’s approach in the current Senate. Powerful Republicans including former railroad lobbyist Sen. John Thune (R-S.D.) lined up against the measure, and it hasn’t been brought up for a vote in the full Senate.

Nevertheless, Rep. Michael Rulli (R-Ohio), whose district includes East Palestine and who represented it as a state senator, said Vance won’t stop advocating for the town.

“It’s been a godsend to have J.D. here on that level because I didn’t have that megaphone to reach people,” Rulli said.