Part of the Jim Crow Museum of Racist Memorabilia, Dr. David Pilgrim’s The Tragic Mulatto Myth is a marvelous survey of American film and literature. See also The Meaning of Mulatto by Erin Bannister:
By the end of twelfth grade, I had adopted the word mulatto, a term that originated from the Spanish word for mule, the ungainly, stubborn, and sterile offspring of a donkey and a horse. Which one of my parents, I wonder, is the donkey?