Why did Trump do better among Northern surburban voters, worse among southern?

[Tetro Kornbluth]

He didn't, it's just that wealthier Southern whites in the suburbs were traditionally more likely to be GOP than those in the North. On the election day therefore some - more economically cautious and liberal minded - of that persuasion flipped in the South while a similar person in the North had been voting for the Dems in Presidential races for quite some time.