This guy's maps are apparently making a big splash on the web. He's taken data from the last census and imposed it on maps of major US cities, tracking what race of people lives where. In some cities the dividing line between black, Hispanic or white is a single street. In others, not so much. His photo site is here.
Given that this guy is -not- a professional cartographer, and given that these maps are SO provocative of comment, one must suspect The Invisible Hand of Self Censorship that there aren't government maps like this commonly available for social and business research types. Personally if I were a cop I'd kill for maps like this, you could plot crimes on them and figure out where to put your guys for best effect, plot what gangs are doing what crimes in what locations, all kinds of things.
Funny how we -never- see stuff like that. One might be excused for the suspicion that maybe solving crimes wasn't the highest police priority.
Here's Phoenix AZ:
Note how there's not really a single race neighborhood in the whole place? Some have more yellow than others, some more blue. Damn racists.
But you don't see this:
This is Chicago, where a certain community organizer got his training on how to be the President and unify the country. Note the intense colors and sharply drawn borders!