One of the most important changes in the food industry in recent decades has been the increase in retailer concentration at the national level. The trade publication Progressive Grocer releases the Super 50 annually, a ranking of the 50 largest food retailers in the U.S., by receipts. In 1997 the top 5 retailers controlled 24 percent of the national market. By 2004 this figure was 46 percent and by 2010, 61 percent.1 Much of this change has been driven by waves of mergers and acquisitions (Franklin, 2001), but it is impossible to overlook the role that big box, low-cost supercenter stores, particularly Wal-Mart, have played.2 Wal-Mart entered food retail with its first supercenter in 1988 and has since grown to become the largest food retailer in the U.S. by a wide margin.