The USDA made a neighborhood-level map of "food deserts"-- communities where a significant portion of residents do not have easy access to large grocery stores and healthy food options. http://www.ers.usda.gov/data/fooddesert/ It would be interesting to see the two maps layered.

Yeah, that divide is extremely well delineated in DC, in an incredibly freaky way. Although I was quite interested to see the diversity of the pixelation in Great Falls which is one of the wealthiest areas of Fairfax County/ DC Suburbs. I suppose if you're really really rich you either take great pains to be in incredible shape or you just let yourself go completely.

I just noticed the same (and made a similar comment in response elsewhere).

I noticed the exact same thing!

It'd be easy plot income levels on the same map to see how the two correlate. It'd be interesting to plot other things like branches of chain restaurants, proximity to gyms, etc too.