It's like a barrage of bad memories from America's past, unwanted flashbacks from the 1960s rattling the notion that civil-rights struggles are a relic of history.
The cruelest of those memories has been stirred in a South Carolina church, where a gunman murdered nine parishioners Wednesday after spending an hour with them in Bible study.
It was painfully poignant for Arthur Price's parish.
He's pastor at the Sixteenth Street Baptist Church in Birmingham, Ala., where four little girls were killed in a 1963 bombing that horrified the country.
Price said his parishioners instantly recognized parallels between the latest killings and those that occurred 52 years ago in their church.
"This city, this community, knows the toll that hatred can take," Price said.
"It's a memory etched into many people's minds who lived through that period. Just like we never forget 9-11. We never forget Sept. 15, 1963."
They weren't alone in noticing the similarity.
President Barack Obama mentioned the Alabama incident while speaking about Wednesday's shootings: "The fact that this took place in a black church obviously also raises questions about a dark part of our history."
He repeated a call for gun control that he himself admitted was futile, given the current Congress. But he said he'd been forced to deliver too many mournful statements after mass-killings and expressed hope the U.S. will eventually reconsider its gun policies.
Moments earlier, the suspected gunman had been caught.
Dylann Roof was arrested at a traffic stop a few hours from the crime scene. An old social-media photo showed him wearing a jacket with patches from apartheid-era South Africa and Rhodesia.
The symbol on Roof's license plate remained relevant in the news Thursday, in an eerie bit of timing. The stars-and-bars flag of the Confederate south still flies outside the South Carolina legislature, and in nine states it's allowed on vanity plates like Roof's.
On Thursday, it could have been allowed in a 10th state — but the U.S. Supreme Court ruled against people suing the Texas state government for that right.
Americans have been prompted to debate just how much has changed in the country, in a difficult year for race relations dating back to last summer's Ferguson riots.
Consider that the unemployment gap between blacks and whites is the same as 1963. Among Fortune 500 companies, less than one per cent have black CEOs.
Deaths during police interventions have prompted a push for officers to wear body cameras — a cause championed by one of Wednesday's victims, Rev. Clementa Pinckney.
The state politician and pastor of Mother Emanuel Methodist Episcopal Church in Charleston took up the cause after the fatal police shooting of Walter Scott.
The tragedy of American race relations is chiseled into the history of Pinckney's church: it was tied to a planned slave revolt in 1822, was subsequently burned to the ground and later attracted prominent civil-rights leaders like Martin Luther King Jr.
Over in Birmingham, Reverend Price said much has changed since the attack on his parish.
It took 14 years to file federal charges in the schoolgirls' killings. Witnesses wouldn't talk. A young white lawyer who denounced the killings was chased out of town.
It took 14 hours to arrest the suspect this time. And the FBI opened a hate-crime investigation.
"Fifty years ago, blacks and whites couldn't sit at the same lunch counter. They couldn't go to the same swimming pools. They couldn't go to the same schools," Price said. "African-Americans couldn't run for the office of mayor or be considered for police commissioner or fire chief."
Today, the police and fire chief of Birmingham are both black.
Other things have changed: the life-expectancy gap has closed, high-school graduation rates are nearly the same. While less than one per cent of Congress was African-American in 1963 it's almost 10 per cent today.
As Price was being interviewed, a two-term African-American president was speaking on TV.
"Many things have changed," Price said.
"Overall, the country is in a better place. Better doesn't mean we've arrived. But it means that things are better than 50 years ago."