For example, I come from a relatively rural area and spent a few months working in Mountain View. At first i thought it was a proverial melting pot relative to home, but then i realized that i never saw any black folks...
Demographics for the area show African American at 2-3%. So if you happen to be black and get hired on at Google, for example, is there sonething wrong with looking for an area where you might relate to your neighbors more or should you optimize for diversity?