In a nation of perceived food abundance, about 4% of the US population still lives in a so-called "food desert," according to data and a mapping tool released May 2, 2011, by the US Dept. of Agriculture. Food deserts are areas where many residents have no access to a large grocery store, due to distance, lack of a vehicle, and/or low income. Convenience stores or other small grocery stores may be nearby, but they tend to carry little if any of more healthful food types such as fresh produce.
USDA evaluated numerous factors for 65,000 census tracts, and found that about 10% of them, home to about 13.5 million people, are food deserts. On the USDA map (which can be viewed from the national to the sub-county scale) you can click on each census tract that is a food desert and get more than a dozen statistics on low food access, such as the affected number and percentage of the overall population, children, those over 65, or housing units. The vulnerable census tracts are scattered all over the country. Local social service agencies may be a good starting point for identifying affected people you can talk with.
For more information and sources on food deserts, see the TipSheet of Feb. 18, 2009.