Maps: Starbucks, Walmart, and more

Via Marginal Revolution, maps representing per capita distribution of Starbucks and Walmart, respectively:


An interesting feature of these maps is that while most areas seem to be saturated with either WM or SB, there's a relative lack of saturation on the east coast -- neither Starbucks nor Walmart has acheived high per capita distribution here. Do east coast shoppers and coffee drinkers have a stronger preference for independents or regional chains?
Here are a couple more maps for comparison--
Median household income (2006 data):


Deaths from heart disease (white males, based on 1997 CDC data):