Kamala Harris may become the first Black woman elected as vice president, but for now she’s still being slotted into a well-worn mold, as President Trump and his allies seek to cast her as “a mad woman.”

Within hours of her joining Joe Biden on the Democratic ticket on Tuesday, Mr. Trump branded her “extraordinarily nasty,” and then “so angry,” as the rhetoric ratcheted up. By Thursday, a Trump campaign fund-raising email called her “the meanest” senator.

All of it played on a racist trope that goes back generations in American culture, and has a complicated history in forging gender identity, power and class. The “angry Black woman” remains a cultural and social fixture, a stereotype that has been used to denigrate artists, athletes and political figures.

“The notion of the angry Black woman was a way — is a way — of trying to keep in place Black women who have stepped outside of their bounds, and who have refused to concede the legitimacy of being a docile being in the face of white power,” said Michael Eric Dyson, the Georgetown professor and author.

The trope, like all stereotypes, is meant to make its subject into something one-dimensional and easier to puncture. It demeans Black women who are perceived as angry by dismissing them as shrews whose opinions do not count because they are pushed to rage by everything, and nothing.

“If you don’t grant us a degree of emotional complexity, then you don’t have to take us seriously, as leaders or as a constituency that has value,” said Brittney Cooper, a professor at Rutgers University and the author of“Eloquent Rage: A Black Feminist Discovers Her Superpower.” “White supremacy is lazy and unoriginal,” she added, “and doesn’t feel the need to ascribe humanity to Black women.”

Ms. Harris has not responded to Mr. Trump’s language, but the Biden camp released a statement Friday evening that referred to Mr. Trump’s “clumsy, bigoted lies.”