US President Joe Biden and Vice President Kamala Harris will sign a bill into law on Thursday afternoon to make June 19th a federal holiday commemorating the end of the legal enslavement of Black Americans.
The bill was passed overwhelmingly by the US House of Representatives on Wednesday after a unanimous vote in the Senate.
It marks the day in 1865 when a Union general informed a group of enslaved people in Texas that they had been made free two years earlier by President Abraham Lincoln's Emancipation Proclamation during the Civil War.
The White House will hold a signing ceremony with Mr Biden and Ms Harris at 8.30pm Irish time.
Mr Biden and his fellow Democrats are under pressure to respond to a slew of Republican-backed state bills that civil rights activists say aim to suppress voting by minorities, and to meaningfully address the disproportionate killing of Black men by police.
Performative danger
"It's important to commemorate emancipation and to encourage everyday Americans to reckon with the history of slavery ... but there is always a danger with these sort of things so they can be performative," said Matthew Delmont, a professor of history at Dartmouth College who specialises in African-American history and civil rights.
Designating Juneteenth a federal holiday will be a "failure" if it just acknowledges the date without spurring action on issues such as police brutality, voting rights, and the racial wealth gap, Prof Delmont said.
The law comes a year after the United States was rocked by protests against racism and policing following the murder of George Floyd, an African-American man, by a Minneapolis police officer.
Juneteenth will be the eleventh federally recognised holiday, joining a list that includes Christmas, New Year's Day, Thanksgiving and Independence Day, as well as days honouring presidents and slain civil rights leader Martin Luther King Jr.
Inauguration day, when the US president is sworn in, is also a federal holiday every four years.
Federal employees will start taking the holiday off this year, observing it on Friday since Juneteenth falls on Saturday, the US Office of Personnel Management said on Twitter.
