If you exclude all of Oakland specifically because it's full of minorities, you're discriminating based on race. If you exclude one tiny neighborhood because it's on the other side of a mountain and is physically a part of a different area than it's administratively a part of, you aren't. Granularity isn't the problem.

And state or regional real estate advertising doesn't work because basically nobody in San Francisco is looking for housing in Los Angeles or vice versa, much less San Francisco and Phoenix.