“We felt it was important to show his face, not to give him any credit, but to show people how normal he was,” said Kari F. Watkins, the museum’s executive director, “It could be anybody. The terrorist among us.”

Aside from his picture, there is his rusty, yellow 1977 Mercury Marquis getaway car. The curators also included a copy of “The Turner Diaries,” a bigoted novel popular on the far right — he had a copy on the front seat of the Marquis — whose white supremacist hero blows up the FBI headquarters.

The bombing remains something of an anomaly. Between Pearl Harbor and the Sept. 11 terrorist attacks, Oklahoma City was the deadliest deliberate attack on the United States, yet it has not been similarly woven into the tapestry of American history.

Sunday marked the bombing’s 25th anniversary, with both historians and those who experienced the attack directly worried that the memory is fading even as the violent ideology that inspired McVeigh grows ever more prevalent.

“In today’s political environment, I hear echoes of the kind of rhetoric that I think inspired the perpetrators of the bombing,” said David F. Holt, 41, the Republican mayor of Oklahoma City. “I think that we all have an obligation to look at Oklahoma City — to look at that scar we have in our downtown — and remember where this all leads when you call other people your enemy, when you try to foster division and difference.”

Most anniversary events were canceled because of the coronavirus outbreak. The annual reading of the names was prerecorded, along with brief remarks by various political figures. Local television stations broadcast the hourlong remembrance video, which was also available online.

Homegrown terrorism is the main factor setting Oklahoma City apart.

“Americans forgot it pretty fast,” said David Neiwert, whose book “Alt-America” chronicles the spread of far-right extremism. “It is a difficult story to tell. It runs up against the whole narrative of American exceptionalism because that was an American terrorist, and Americans like to think that they don’t do that sort of thing, only guys in turbans do that.”

Convicted of murder and other crimes in federal court in 1997, McVeigh was executed three months before the attacks on Sept. 11, 2001.

McVeigh, 26 at the time of the bombing, grew up a skinny, bullied kid in a typical middle-class home outside Buffalo, New York. He joined the Army at 20, earning a Bronze Star as a gunnery sergeant in the Persian Gulf War.

While in the military, McVeigh grew increasingly obsessed with guns and hostile toward the U.S. government. Washing out of an audition for the special forces set him on the path toward the paramilitary wing of the white power movement.

Lacking a girlfriend or a promising job, he penned bitter letters. “Is a Civil War imminent?” he wrote to one newspaper. “Do we have to shed blood to reform the current system? I hope it doesn’t come to that. But it might.”

Two sieges by U.S. law enforcement agents against suspected armed compounds — Ruby Ridge, Idaho, in 1992 and Waco, Texas, in 1993, where 86 people died — enraged him.

So he plotted revenge. On the second anniversary of Waco, he used fertilizer to construct a 7,000-pound bomb in a Ryder truck, parking it outside the Alfred P. Murrah Federal Building in downtown Oklahoma City.

He lit the fuse, then scurried away, and a stupendous explosion ripped through the city at 9:02 a.m., tearing off the building’s mostly glass facade and pancaking its nine stories. The building housed the offices of 17 federal agencies as well as a day care center, where 15 of the 21 children present perished. Another four children died elsewhere in the building.

McVeigh, who never expressed remorse, called the children “collateral damage” during some 70 hours of jailhouse interviews with Lou Michel and Dan Herbeck, investigative reporters for The Buffalo News who wrote “American Terrorist: Timothy McVeigh and the Oklahoma City Bombing.” He expressed disappointment that the bombing failed to ignite a widespread anti-government uprising, a far-right fantasy.

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Michael L. Walker, 49, now the deputy chief of operations for the Oklahoma City Fire Department, was a young firefighter a few blocks from the eruption. Like many people, he first thought it was a natural gas explosion. His fire engine flew along streets turned aqua blue from blown-out windows as it raced toward the plume of black smoke.

Walker spent all day and much of the night searching, first for the living, then for the dead. Occasional toys jutted from the rubble. In the ensuing days, grieving parents told firefighters what their toddlers had been wearing.

“Every day was a grim day, but we knew we had a job to do,” he said. “There is still a sense of loss for those families.”

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The memorial includes rows of 168 empty bronze, glass and stone chairs, including 19 little ones, in a grassy field adjacent to a reflecting pool where the building stood. The blast also injured hundreds of people.

The bomb detonation threw Dennis Purifoy, now 68 and retired, to the floor of the Social Security office. At first he thought a computer had exploded and could not understand why nobody responded when he yelled for help. Stumbling through the darkness and dust, he eventually found other survivors and an emergency exit but was unable to help one bloodied woman who perished.

Sixteen people in his office died, and if he no longer thinks about it every day, he does worry that the ideology behind the attack has found new adherents.

“That awful underbelly of American life that has been there for a long time is still there and it is still dangerous,” he said. He noted that members of the far-right, white supremacists and neo-Nazis like those who marched in Charlottesville, Virginia, in August 2017 continue to spout the same anti-government, anti-Semitic rhetoric. “Ideologies are sometimes not just ideologies. They result in awful actions and we need to be vigilant about that.”

When the FBI traced the Ryder rental used as the bomb, they discovered McVeigh jailed in a small Oklahoma town. He had been detained by a vigilant state trooper because his getaway car had no license plate and no documents and he was wearing an unlicensed Glock pistol.

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Terry L. Nichols, now 65, an army buddy of McVeigh, was sentenced to life in prison as an accomplice and Michael J. Fortier, who knew about the plot but did not report it, was released from prison in 2006 after serving more than 10 years of a 12-year sentence. He and his wife, Lori, were cooperating witnesses in both trials.

There is a continued debate whether the FBI traced everyone connected to the plot. McVeigh maintained that he acted largely alone, a model of the “leaderless resistance” strategy that white supremacists adopted in the 1980s.

To some extent, law enforcement agencies perpetuate a falsehood when describing attackers like McVeigh as “lone wolves,” said Kathleen Belew, a University of Chicago historian and author of “Bring the War Home: The White Power Movement and Paramilitary America.”

That discounts the far-right ecosystem both online and on the ground that nourishes such killers. “We can see that they are quoting the same texts, that they have all these social ties with one another, that they are working for the same objectives,” Belew said. “As long as society buys into this fiction of the lone wolf, there is no movement to confront.”

The nation grieves the dead, she said, but has failed to take the difficult step of uprooting the cause.

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White supremacists praise McVeigh as an action hero, and consider his body count something to beat, Herbeck said.

Law enforcement agents who arrested the founder of the violent, far-right group Atomwaffen in 2017 found a framed picture of McVeigh on his dresser. That worship spread overseas, too.

While researching German extremism in the early 2000s, Cynthia Miller-Idriss of American University found shirts printed in the manner of a soccer score. Small white lettering said “McVeigh vs. Government” above the big red numbers 168:1, comparing his death toll with his execution.

In Oklahoma, the attack shifted the mindset toward that kind of radicalization.

“We should recognize rising hate,” Sen. James Lankford, R-Okla., said on the memorial recording. “How do we identify things like anti-Semitism, racism or hatred for government? We as a culture need to recognize those moments and not just allow them to lie dormant, but to engage.”

Studying the attack has been mandatory in Oklahoma schools since 2010. No similar effort occurred nationally.

Hence, McVeigh haunts every school or mall shooting, said Michel of The News. If you drew a line, he said, you would find that “McVeigh is at one end of that line, at the beginning, and you can bring it right up to today.”

This article originally appeared in The New York Times .