This map is one of a series of maps that I found in an article titled "The Storefront Index, on the CityCommentary web site. The maps were also described in this Washington Post article,
In articles written between 2008-2011 on this blog, such as this, you can see the Tutor/Mentor Connection's efforts to show business locations in different parts of Chicago, who are assets who could be helping tutor/mentor programs grow in areas around each location. I've not found a web site mapping business sites, so this one is possibly a valuable tool for those creating map stories like I do.
Update: 4/28/2016: The Washington Post hosts an article showing winners and losers in the US Housing market, using maps to help build an understanding on a city-by-city basis and emphasizing the unequal impact on minorities vs Whites. See story.