Democratic New York Rep. Alexandria Ocasio-Cortez made a false claim involving Washington D.C. and slavery while making the case that the District of Columbia should be a state.

The freshman congresswoman tweeted Thursday that D.C. was the first territory to “free the enslaved,” which is not true.

“DC was the 1st territory in the United States to free the enslaved,” Ocasio-Cortez tweeted. “It’s where Black Americans fled the tyranny of slavery & towards greater freedom, to DC. Yet today it’s where 2nd class citizenship reigns, and the right to vote is denied.”

DC was the 1st territory in the United States to free the enslaved. It’s where Black Americans fled the tyranny of slavery & towards greater freedom, to DC. Yet today it’s where 2nd class citizenship reigns, and the right to vote is denied. It’s time to recognize DC statehood. https://t.co/AkfaRHw38C — Alexandria Ocasio-Cortez (@AOC) September 19, 2019

In reality, Vermont became the first U.S. territory to abolish slavery in 1777, and Pennsylvania was the first state to officially end the practice in 1780. Washington D.C. was not officially a territory until 1790. (RELATED: Bipartisan Duo Files Lawsuit Against Ocasio-Cortez For Blocking Twitter Followers)

Washington D.C. was actually one of the last territories in the U.S. to abolish slavery. The slave trade ended in D.C. in 1850 as part of the Compromise of 1850, and it officially became illegal to own slaves in the district in 1862 after the passage of the D.C. Emancipation Act. (RELATED: Ocasio-Cortez Blames Republicans For DC Flooding)

Progressives have long argued that Washington D.C. should become a state and receive representation in Congress. The House of Representatives endorsed D.C. statehood in March as part of a sweeping voting rights bill.