I feel like you would get a similar result if you did a map of Paris or other big european cities, I'm not sure it's an american thing. I think over here we just don't like/can't compile that kind of racial data. I would be more interested in counter-examples: cities were the melting pot is the rule.
Making race maps in Europe would get you shot, your family hanged and all your friends deemed social outcasts forever. For example: the Swedish crime prevention board (BRÅ) no longer publish crime statistics containing ethnic background information. They stopped a few years ago (2006) when the PC media found out that africans and arabs were way, way over-represented in all crime categories. This is due to political c…
Stop and Frisk in NYC overwhelmingly targets blacks and latinos, to the point where it's been declared unconstitutional, for example.