The news of freedom came late to more than 250,000 enslaved black people in Texas.

On June 19, 1865 — more than two years after President Abraham Lincoln had issued the Emancipation Proclamation, freeing the slaves in Confederate states — Maj. General Gordon Granger stood at the Headquarters District of Texas in Galveston and read “General Order No. 3”:

“The people of Texas are informed that, in accordance with a proclamation from the Executive of the United States, all slaves are free.”

Black people who heard the news erupted in celebration.

“They spent that night singing and shouting," remembered Pierce Harper, a formerly enslaved woman, in 1937, according to “Slave Narratives” interviews collected by the Works Progress Administration. “They weren’t slaves no more.”

Ever since, African Americans across the country have marked that day of independence with a holiday known as Juneteenth. President Trump announced Wednesday that he plans to resume holding his political rallies — in Tulsa on June 19, the celebratory day of Juneteeth. Yet Tulsa is the site of one of the worst episodes of racial violence in U.S. history: the 1921 Race Massacre.

The announcement that Trump would hold a political rally on Juneteenth in a city — where as many as 300 black people were killed by mobs of white people — shocked some historians.

“It’s almost blasphemous to the people of Tulsa and insulting to the notion of freedom for our people, which is what Juneteenth symbolizes,” said CeLillianne Green, a historian, poet, lawyer and author of the book, “A Bridge: The Poetic Primer on African and African American Experiences.”