In a scenario that looks uncannily like the spread of a global pandemic, the economist Thomas Holmes has prepared a dynamic map simulation showing the spread of Wal-Mart stores throughout the United States. Starting at the epicenter in Bentonville, Arkansas, where Sam Walton opened his first store in 1962, giant boxy Wal-Mart stores have now multiplied to the point where the average American lives less than seven kilometers from an outlet.