He'll be joined by California Senator Kamala Harris, Watchmen showrunner Damon Lindelof, Luke Cage actor Alfre Woodard, writer and comedian Baratunde Thurston, Chicago P.D. actor Sophia Bush, and activist Dr. Tiffany Crutcher, among others.
The event will take place at 7 p.m. ET and will be streamed on Instagram, corresponding with President Donald Trump's rally in Tulsa, which had originally been scheduled for the holiday itself on June 19.
Trump's decision to hold a Juneteenth rally in Tulsa, the site of the 1921 Tulsa Race Massacre—when mobs of white people attacked thousands of black Tulsans and killed an estimated 300—during a time when marches and gatherings have continued around the country in protest of systemic racism and police brutality, was called out by Harris and others as insensitive and offensive.
Trump said on Thursday that he made Juneteenth—which is recognized as a holiday or day of observance in 47 states and the District of Columbia—famous during an interview with the Wall Street Journal.
"I did something good: I made Juneteenth very famous," he said (h/t Maegan Vazquez of CNN). "It's actually an important event, an important time. But nobody had ever heard of it."
But when Trump asked an aide during the interview if she had ever heard of the holiday, she responded that the White House had put out public statements recognizing the holiday each year of his presidency.
Juneteenth commemorates June 19, 1865, when Union general Gordon Granger arrived in Galveston, Texas, with his troops and informed those enslaved in the state that they had been freed by executive degree. While the Emancipation Proclamation was about two years old at that point, its enforcement had not yet reached Texas.
Because Texas hadn't seen any major battles or fighting during the Civil War, the area didn't have a large presence of Union soldiers and slavery thus continued beyond the end of the war. Granger's arrival formally ended that and preceded the 13th Amendment—abolishing slavery—and the Civil Rights Act of 1866.