“YP lists 880 stores in their “grocery store” listing with Detroit city addresses.”
My address is “Tallahassee.” I live 25 miles from Tallahassee. I have houses in “Woodville” and “Crawfordville.” But those houses are ten and twelve miles from those places. The article I’m quoting from probably referred to the actual area of Detroit, which is bounded by interstate highways separating it from the surrounding areas.
Well, here’s the map of the City of Detroit:
http://www.maptechnica.com/us-city-boundary-map/city/Detroit/state/MI/cityid/2622000
Here’s the list of 880 stores listed with YP as “grocery stores” with Detroit, MI addresses:
http://www.yellowpages.com/detroit-mi/grocery-stores?page=1
It’s pretty easy to see whether they’re in the City of Detroit or not.