Donald Trump is so dependent on racial and ethnic antagonism that without it, he would be a marginal figure, relegated to the sidelines. Trump’s constant demonization of Black people and immigrants has inured the public to the fact that he is the first — or certainly the most explicit — modern president and party nominee to transparently generate, not to mention exacerbate, fear and white animosity toward people of color. Despite his appeal to a small if potentially crucial segment of Black and Hispanic men, racial bigotry has been central to Trump’s appeal from his initial quest, in 2015 and...