A Venti-nonfat-caramel-Frappuccino is no more than 20 miles away from most Americans.
University of Washington doctoral candidate James Davenport posted graphics on his blog charting Starbucks-owned locations in the country two ways: a Delaunay triangulation and Voronoi diagram (fancy names for cool diagrams). As the Atlantic Wire reports on the former, "[T]he green dots representing Starbucks cluster around big cities, and with the connecting lines, the map basically looks the same as a regular old map of the U.S."
This second diagram can determine the places farthest away from Starbucks. According to Davenport's blog, the most frappuccino-lacking town is Alta, Wyoming. (Although he noted in an email that the actual most isolated spot is in nearby Grand Teton National Park.)
One might define urbanization in the modern era as the distance to the nearest Starbucks. An "urban" environment would therefore be anyplace within a 20 mile radius. Yes, more than 80% of the USA (that's 250,000,000 people) live within 20 miles of a Starbucks.
(h/t Fast Company's Co.Design)