It also has a popular narrative attached to it... the "tragic mullatta" that persisted until the Civil Right era. The narrative was usually about a woman who passes as white but is exposed as a mullatta or octoroon dooming her love or marriage plans. Sometimes the woman is aware of her identity from the beginning and sometimes (more dramatically) unaware until it's revealed to her.
It wasn't a completely reactionary narrative since it was very handy in dramatizing the hierarchy of racial status in American culture. The 19th century play "The Octoroon" by Dion Boucicault was one of the most popular plays of the 19th century along with "Uncle Tom's Cabin" and both were connected in different ways to pro-abolitionist sentiment. There's also "Show Boat" "Imitation of Life" and others.
The one constant was that the story always ended tragically for the Mulatta. But apparently when the Boucicault play was performed in England during the 19th century there was a happy ending for the mixed race couple.