Carrie Kilman has writen an excellent article for tolerance.org that succinctly summarizes the issue of food redlining ... the growing trend of large-scale supermarkets moving out of low-income neighborhoods, leaving those neighborhoods without any access to fresh, healthy, low-cost food. This isn't something I have discussed on this blog, but is a growing problem. It would be easy to explain away if it were a matter of pure economics, but this article says that there isn't the data to support that myth.
There are some fantastic non-profit organizations that are working to solve this issue. A local organization, The People's Grocery, was recently profiled in the San Francisco Chronicle for their fight in the West Oakland area to bring fresh fruits and vegetables and natural foods to the citizens there.
The People's Grocery article and Carrie Kilman's article are well worth reading to give you an idea of this growing issue.