"Senator Tina Smith, Senator (Cory) Booker, Senator Kamala Harris and I will introduce the Juneteenth National Independence Day Act to make Juneteenth a federal holiday," Markey said via Twitter.
Markey said the new bill was "[j]ust one step to begin to right the wrongs of the past to ensure justice in the future".
Also on Friday, New York City Mayor Bill de Blasio announced that Juneteenth will be an official holiday for city workers and schoolchildren next year, and the city will form a new commission to examine its history of racial discrimination.
Juneteenth commemorates the end of slavery in the United States on 19 June 1865. On that date, Union Army Maj. Gen. Gordon Granger told a group of black slaves in Galveston, Texas, that the 1861-65 Civil War had ended and that they were free in accordance with President Abraham Lincoln's Emancipation Proclamation of 1863.