In the summer of 2013 I participated in the National Day of Civic Hacking at the Adler Planetarium. This program brought together students from around Chicago and partnered them with scientists and hackers to address problems in their communities.
I joined a team exploring ways of improving Chicago residents' access to fresh produce. Large numbers of Chicagoans have no grocery stores or produce markets within reasonable walking distance (we used a working definition of 1 mile). The students were interested in creating a map of these so-called food deserts so that programs like Fresh Moves could better target those in need.
Chicago Data Portal
Chicago has been a leader in making municipal data publicly available through its Data Portal. From this site we were able to get a listing for all active business licenses. We filtered this list by business type, however we found this list was missing a number of stores. We supplemented the list by also filtering for businesses with names of known chain stores and produced a list of 166 Chicago grocery stores with known locations.
We used the Google Maps API to create an interactive map of Chicago grocery stores and food deserts. To map the desersts we overlayed a map of Chicago's boundaries and used pyKML to create a second, inverted overlay of regions within 1 mile of each identified store (see map to the right). Hide the grocery store markers for a better view of the grocery deserts, colored in blue. The map is far from perfect. It portrays O'Hare airport as a large desert and tends to find deserts at the edges, though there may be stores located just outside city limits. Still, not a bad result for a few hours of work!