When I was living in San Diego about a decade ago, Z90 was pretty much an urban station, though they classified themselves as rhythmic. There was also the rhythmic oldies station Magic 92.5, which is still around. Later on, 98.9 was hip-hop station, but I was long gone when they came around. I realize San Diego is only about 7% black, but with a large Hispanic population that likes hip-hop, I'd think one could survive.