Other than 'they're racist' or whatever. In almost every state and area imaginable, where there's a high black or Hispanic population, there is a higher than average Trump vote in the Republican primary. We know Republican primaries are >90% white most of the time, so these are not necessarily black or Hispanic voters who have 'a great relationship' with Trump. Is it because these areas fit the Trump demographic - disaffected, poorer, blue collar, less education, etc? Or is there something else behind it?
Why bother asking if you already know the answer?