Not sure where you get 8 miles vs 11 miles (maybe the definition of a rural food desert?).
> Low access is characterized by at
least 500 people and/or 33 percent of the tract population residing more than
1 mile from a supermarket or large grocery in urban areas, and more than 10
miles in rural areas
> Low access is characterized by at least 500 people and/or 33 percent of the tract population residing more than 1 mile from a supermarket or large grocery in urban areas, and more than 10 miles in rural areas
(source: https://www.ers.usda.gov/webdocs/publications/45014/30940_er... )
Interestingly enough, this is measured by the euclidian distance, not by the actual number of miles required to travel.