A classic case of false logic. The main cause of crime is poverty (Wall st and the white house notwithstanding). So even if your meme is correct (and it is disputable). It is quite understandable that poor cities with higher amounts of ethnic communities will be left-wing and vote for ethnic candidates. Did you really think that they would vote for the white billionaires of the GOP?
Okay, lets put it another way. Suppose I point out "ATTRACTIVE WOMEN WITH BIG TITS MARRY SUCCESSFUL RICH GUYS" It sounds plausible. The head cheerleader and the quarterback are American dating cliches. Does that mean that going with poor guys makes women ugly and their tits shrink?

I hope you have a better source than a meme.

Do you see a pattern?