NEW YORK — No one has been hurt or killed. But the wave of mail bombs targeting prominent Democrats this week has angered and dismayed some of the people affected personally by past acts of political violence in the United States.

In the past 60 years alone, there have been scores of deadly incidents motivated by ideology. The perpetrators range from Ku Klux Klan racists to members of the far-left Weather Underground to anti-abortion extremists who killed abortion-providing doctors.

On Friday, federal authorities took a Florida man identified as Cesar Sayoc, 56, into custody in connection with the package bombs. Court records show Sayoc has a history of arrests for theft, illegal possession of steroids and making a bomb threat.

The mail-bomb scare reopened old wounds for Lisa McNair, whose life was shaped by a deadly blast that occurred a year before she was born: the Klan bombing that killed four black girls at 16th Street Baptist Church in Birmingham, Alabama, on Sept. 15, 1963. Her sister, Denise, just 11 years old, was the youngest victim.

“It’s like, ‘Ugh, again.’ When are we going to get this right?” McNair said. “It’s been 55 years since Denise was killed. Why do we keep going there in America? Why do we keep going there as a world and human beings?”

The United States, founded in a war that began as a political rebellion, likes to pride itself on a political system that discourages violence and emphasizes dialogue — no matter how loud and contentious. But in times of deep division throughout American history, angry words have occasionally turned to angry acts and left devastated citizens in their wakes.

Some of those directly impacted by political violence say they struggle to remain optimistic in this contentious era. Others say their perspectives have evolved over time, and they believe they have insights to share.

The Rev. Rob Schenck was a fiery leader in the anti-abortion movement 20 years ago when an extremist’s bullet killed abortion provider Dr. Barnett Slepian as he heated soup in the kitchen of his home outside Buffalo.

The killing changed Schenck. He concluded that the language of his cause — “innocent, deliberately hyperbolic rhetoric meant to drive home a point”— produced deadly consequences.

Schenck said he’d thought in recent weeks about sending a memo to President Donald Trump, to convey the lesson he’d learned firsthand and recommend a toning down of vitriolic oratory.

“The president may honestly believe that no one who supports him is capable of acting with lethal violence, but the sad fact is he can never know that,” Schenck said.

Hearing about the pipe bombs “sickened” him.

“My first thought was, `Here we go again.’ In the worst possible way,” he said.

Another abortion provider, Dr. George Tiller, was shot dead by an abortion opponent in Wichita, Kan., in 2009.

One of Tiller’s colleagues, Julie Burkhart, currently operates abortion clinics in Wichita, Oklahoma City and Seattle. She says the mail-bomb scare has prompted her to double-check security measures.

“I’m scared to death for this country,” Burkhart said in a telephone interview.

“The gulf between Republicans and Democrats, pro-choice and anti-choice — it’s a huge canyon now,” she said. “There’s all this pent-up anger and frustration, and we’re going to be taking it out on each other even more.”