News analysis by Lisa Lerer and Maya King in the NYT:

The audience of Black journalists was prepared for a combative exchange well before Donald J. Trump took the stage on Wednesday for an interview at their annual gathering in Chicago.

Yet when Mr. Trump, just minutes in, began questioning Vice President Kamala Harris’s racial identity, there was an instant ripple of reaction — a low rumble that grew into a roar of disapproval. . . .

The audacity of Mr. Trump, a white man, questioning how much a Black woman truly belongs to Black America was particularly incendiary.

And it evoked an ugly history in this country, in which white America has often declared the racial categories that define citizens, and sought to determine who gets to call themselves what.