The image is a screenshot from the USDA website “Food Desert Locator“. Go to the website for the interactive map, where each area is clickable to see the statistics.
From wikipedia.org:
A food desert is any area in the industrialised world where healthy, affordable food is difficult to obtain. It is prevalent in rural as well as urban areas and is most prevalent in low-socioeconomic minority communities, and is associated with a variety of diet-related health problems.[1] Food deserts are also linked with supermarket shortage.
(This is also posted on the N.Tx.VegetableGardeners site)
