On Saturday, he posted a statement for the June 19 holiday, which marks the date that news of the Confederate surrender reached the last enslaved Black people - when Union soldiers brought the news of freedom to Galveston, Texas, in 1865 some two and a half years after the Emancipation Proclamation legally freed slaves in the Southern states.
"Juneteenth marks both the long, hard night of slavery and subjugation - and the promise of that brighter morning to come," Biden's statement said. "It's a day of profound weight and power. Today and every day, we must work to ensure our nation finally lives up to its promise of equality for all."
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The Senate unanimously passed the measure to make Juneteenth a federal holiday on Wednesday, followed by the House in a 415-14 vote, before it headed to the Oval Office for Biden's signature.
On Thursday, he and Vice President Kamala Harris delivered remarks in the East Room of the White House after making Juneteenth the country's 12th federal holiday - the first creation of a new U.S. national holiday since Martin Luther King Day in 1983, Biden noted.
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"Throughout history, Juneteenth has been known as many things: Freedom Day, Liberation Day, Emancipation Day," Harris, 56, said. "And today, a national holiday."
"I have to say to you, I have only been President for several months, but I think this will go down, for me, as one of the greatest honors I will have as President - not because I did it, you did it, Democrats and Republicans," Biden said. "It's an enormous, enormous honor."
Noting the overwhelming bipartisan support of the measure, he added: "I hope this is the beginning of a change in how we deal with one another."
Harris explained that the freedom granted that day in 1865 was significant in part because of how long it took.
"Yes, on that day the enslaved people of Galveston, Texas, learned that they were free," she said, "but in fact two-and-half years earlier the Emancipation Proclamation ended slavery in the south."
Harris added: "For more than two years, the enslaved people of Texas were kept in servitude ... and then on that summer day, 156 years ago, the enslaved people of Texas learned the news. They learned that they were free. And they claimed their freedom."
"It was indeed an important day," the Vice President concluded.