Two branches of government haven't acted in concert this speedily at least 10 years.

Driving the news: The Senate passed a Juneteenth national holiday on Tuesday, the House followed Wednesday, President Biden signed it Thursday, and Friday is an official federal holiday (although the Postal Service will operate, saying there wasn't time to shut down).

• The annual holiday will be June 19. Because that falls on Saturday this year, the government is observing it the day before.

Why it matters: The holiday is a way future generations will remember America's year of racial reckoning.

• Juneteenth National Independence Day is a permanent marker of a cultural shift that was swifter and surer than we could have imagined before the police killing of George Floyd mobilized millions.

Axios spoke with Harvard law professor Annette Gordon-Reed, who attended Thursday's East Room ceremony, and other historians about the dizzying pace of passage.

• "All of a sudden, I was getting texts, messages — and an invitation to the White House," said Gordon-Reed, author of the historical memoir "On Juneteenth," a current New York Times bestseller.
• "It really matters to young people, who will grow up seeing Juneteenth alongside July 4, Memorial Day and Martin Luther King Jr. Day."

Edgar Villanueva, author of the Decolonizing Wealth: Indigenous Wisdom to Heal Divides and Restore Balance, said slavery and Native American removal not only affected people of color, but also the potential growth of a country as a whole.

• Juneteenth today, he said, should be a time to reflect that, "we've continued to find ways to profit off of the backs of black people in this country."

The newest federal holiday commemorates June 19, 1865 — the day Union Maj. Gen. Gordon Granger rode into Galveston, Texas, with word that the Emancipation Proclamation had been signed by President Abraham Lincoln more than two years before.

• For years, Juneteenth has been celebrated in Houston and Galveston to commemorate General Order No. 3, issued a month after the formal end of the Civil War. Galveston one of the last places in the U.S. where enslaved people learned of their emancipation.
• Rep. Sheila Jackson Lee (D-Texas) who sponsored the national holiday bill in the House, told Axios Juneteenth becoming a national holiday affirms the experiences of people of Houston and Galveston — the descendants of those who celebrated the first Juneteenth.
• Ibram X. Kendi, Boston University professor and author of "How To Be an Antiracist," told Axios he was elated that the holiday has finally come to fruition, but added: "I think we'll be in a battle over how we celebrate Juneteenth and how we utilize this day."