More guerrilla art project than serious statistical study (and somewhat dated at this point), Benjamin Edwards' The World of Wal-Mart is nevertheless an interesting and vivid glimpse at where many familiar consumer items come from. Edwards' mission, on October 15, 2001:

Visit as many Wal-Marts as possible in one day by following the rule: “Go to the nearest Wal-Mart from your present location.”

Inside each store, count as many objects as possible while noting their countries of origin.

The end result is an entertaining travelogue and a big, colorful map, where countries are sized in proportion to the percentage of products they contributed to Edwards' sampling of Wal-Mart locations.

For much more on U.S. trade with and investment in other countries, see pages 74-79 of the 2007 World Almanac and Book of Facts.