My wife does school based nursing.
She spends a lot a time counseling students on healthy diets but a lot of her students live in food deserts.
A food desert is defined as:
A district in an urban or rural setting with little or no access to large grocery stores that offer fresh and affordable foods needed to maintain a healthy diet. Instead of such stores, these districts often contain many fast food restaurants and convenience stores.
I've been through a lot of such areas in my travels to and from homes.
Whenever there are pawn shops or cash advance stores on every block, it's also a pretty good bet that you are in the midst of a food desert.