Last year, President Joe Biden signed the Juneteenth National Independence Day Act, which establishes a holiday that commemorates the end of slavery in the US.
So what is Juneteenth, how did it become a holiday and what do people do to celebrate it?
What is the origin of Juneteenth?
On 19 June 1865 - months after the northern US states defeated the slave-owning South in the US Civil War - enslaved African-Americans in Galveston, Texas, were told they were free.
That act of liberation came more than two and a half years after President Abraham Lincoln issued the Emancipation Proclamation, declaring all enslaved people in the rebellious states to be free.
The declaration by General Gordon Granger to bring the Emancipation Proclamation into effect in the state of Texas is seen by many as the end of slavery.
The day became known as Juneteenth, a word created by joining the words "June" and "nineteenth" together.
How did it become a federal law?
Juneteenth was first recognised as a state holiday in Texas in 1980.
In the decades since, every state but South Dakota formally recognised Juneteenth as a state or ceremonial holiday.
When he was the senator for Illinois, Barack Obama co-sponsored legislation to make Juneteenth a national holiday, but the law was never passed - even after he became president.
But the legislation gained momentum after Black Lives Matter protests around the country in the summer of 2020.
In the lead-up to 19 June 2021, both chambers of the US Congress moved swiftly to pass the bill and - with the signature of President Biden, it became law.
It is the first new federal holiday since Martin Luther King Jr Day was established in 1983.
The attempts to have Juneteenth declared a federal holiday were however decades in the making.
In 2016, 89-year-old Opal Lee walked from Texas to Washington DC to raise awareness and encourage lawmakers.
She walked 2.5 miles (4km) each day - representing the two and a half years that it took for enslaved people in Texas to learn they had been freed.
"I've got so many different feelings all gurgling up in here," Ms Lee said after Congress approved the new federal holiday.
"I don't know what to call them all. I am so delighted to know that suddenly we've got a Juneteenth.
"It's not a Texas thing or a black thing. It's an American thing."
Why does Juneteenth matter?
The ending of slavery did not do away with racism, and in the years after emancipation, so-called Jim Crow laws were created to separate black people from white society and limit their civil rights.
The legacy of those laws is still being dismantled.
The deaths of George Floyd, Breonna Taylor and other African Americans at the hands of police have spurred anti-racism protests.
It also comes as a cultural debate rages over the history of slavery and how it should be taught in American schools.
How is it celebrated?
Juneteenth celebrations and traditions vary across the US. In some states there are parades, and people gather for food and to play games.
As well as public readings and singing, picnics and church services, in some states rodeos, contests, concerts and parades are also organised.
Food also plays an important part, with barbecues being one of the most popular ways of marking the day with family and friends.
The most famous dish is called "the Marcus Garvey salad", named after the black activist and made with red, green, and black beans.