On June 19, 1865, with fighting in the American Civil War largely over, a Union army general declared all slaves in Texas were now free.
The day, now known as Juneteenth, celebrates the official end of slavery in the United States — even though it was not officially abolished until the constitution was amended later that year.
Many people mark the day with outdoor festivals and parties.
The act of freeing slaves in Texas was a significant moment because the state was so remote and Abraham Lincoln’s Emancipation Proclamation in 1863 had not been widely enforced there.
Dr Scot Brown, Associate Professor at UCLA’s Department of African American Studies, told Euronews the day had become an opportunity to talk about what freedom means.
“The Confederacy was still at war with the Union and Texas was one of the last states to fall,” he said.
“So even though there was a proclamation the Texas plantations weren't really forced to give up enslavement until roughly around this time of the year in 1865.”
Juneteenth is now an official holiday in Texas and unofficially observed across the United States, but campaigners have long believed it should be recognised by the federal government in a similar fashion to Independence Day or Labor Day.
This year, state governors in New York, Pennsylvania and Virginia recognised it as a paid day of leave for state employees.
It came after a month of demonstrations against racism and police brutality around the country following the death of George Floyd.
Brown said the protest had presented “an opportunity for us to think about what freedom means for us today”.
He said: “So are we talking about economic freedom, are we talking about questions of poverty, are we talking about issues of police brutality, are we talking about voting rights?
“All those things factor into how we think about what freedom means around this time of the year right now.”
But although the campaign for recognition is gaining traction and companies including Nike and Twitter have told staff it will be a permanent paid day off, it will take an Act of Congress to create a new federal holiday.
A tweet by New York congressional candidate Jamaal Bowman calling for Juneteenth to become a national holiday has been retweeted over 150,000 times.