What happened in Tulsa, Oklahoma, in 1921 was the most shocking racially motivated mob violence in American history.
Worse still, for many decades it was the massacre that the United States refused to acknowledge; the tragedy that was never taught in the country's history classrooms.
The victims weren't just killed. Their lives and legacy were erased, historical revisionism on a scale that still shames this country. Even in a year that has witnessed a great racial reckoning, what happened in this city is an open wound.
100 years ago to the day, this suburb of Tulsa in Oklahoma was a smoking ruin. Thirty city blocks had gone up in flames. Three hundred African Americans - perhaps many more - were shot or burnt alive, and thousands more were forced to flee.
The white mob - fuelled by white supremacist hate and acting as vigilantes - destroyed Greenwood. It was renowned as one of the most successful and prosperous black neighbourhoods in the United States, so wealthy that it was nicknamed the 'Black Wall Street.'
But by first light on June 1, 1921, it was levelled, with bodies scattered along the roads.
A century on, Kristi Williams has a fierce determination that justice should be delivered to the people of her community. She is a small woman with a big heart and a passion for her cause. Her great aunt was a survivor of the atrocity.
We walked the streets of Greenwood and she told me that the US government must pay reparations to a new generation of African Americans.
Her argument is simple: white people enriched themselves from slavery and the sustained mistreatment of black Americans. Now that debt must be settled.
'100 years! 100 years for us here in Greenwood is just really another reminder of what has not been done' - community activist Kristi Williams
President Joe Biden has spoken tonight at a remembrance event in Tulsa. He avoided talking about reparations but he made clear that history needed to be remembered.
“For much too long,” he said, “the history of what took place here was told in silence, cloaked in darkness. But just because history is silent it doesn’t mean that it did not take place. While darkness can hide much, it erases nothing.”
The president added: “My fellow Americans, this was not a riot, this was a massacre.”
Remarkably, today there are still survivors of the massacre, who have led the campaign and provided vivid first-hand testimony, including 107-year-old Viola Fletcher. Last week, she provided evidence to Congress, saying she has seen the best and the worst of America in her long life.
But radicals say that a presidential visit isn't good enough, believing that an official apology is just another whitewash, and that racism is built into the fabric of American society and must be confronted.
On Monday, the controversial and incendiary black activist, Malik Zulu Shabazz, spoke here at an event to mark the centenary. Just listen to his rhetoric. It is not known how many share his views - and his critics say he is a dangerous anti-Semite - but Shabazz is warning of new racial unrest on a massive scale.
If black people don't get justice, 'these tornadoes are gon rip this state from border to border', Malik Zulu Shabazz, from the New Black Panther Party, tells a crowd
Many black residents here insist that justice has never been served. No one was ever charged with inciting the violence or with murder. Courts turned a blind eye. There was a national silence.
Only in recent years have historical commissions properly sought to investigate the events of 1921. A new effort will begin on Tuesday to locate mass graves.
Those who live in Greenwood say there is a long way go to end the racism that has been the bedrock of Oklahoma since the state's very beginnings.
Nehemiah Frank, editor of Black Wall Street Times, says 'systemic racism has been the culture of Oklahoma'
The fight for justice for Greenwood has made progress. The white race riot of 1921 is part of the national conversation for the first time in a century.
But it is just a start. The ultimate objective, according to activists like Kristi Williams, is to ensure that white America pays its historical debt and funds the resurrection of the very black communities it destroyed.