New York City Mayor Bill de Blasio has announced that Juneteenth - the 19 June date which marks the end of US slavery - will become an official holiday.
Several states already observe the day as an official holiday and there is a push to declare it a national holiday.
Mayor de Blasio said in a press conference on Friday that the date would be marked as an official city holiday beginning in 2021, and will also be a public school holiday.
Media playback is unsupported on your device Media caption Juneteenth: 'This is such a change in history'.
Earlier this week, New York Governor Andrew Cuomo signed an order making Juneteenth - also known as Emancipation Day and Freedom Day - a paid holiday for state workers.
In Pennsylvania, Gov Tom Wolf has also signed an order making Juneteenth a holiday for state workers.
In Washington, the most senior Republican in the Senate said on Thursday that he would introduce a bill to make Juneteenth a federal holiday. »