In terms of revenue, CVS/Caremark (formerly CVS Corp.) is the No. 2 drug store in the U.S. (after Walgreens). But when it comes to the number of stores, CVS/Caremark is the leader with about 5,383 stores in 33 states and the District of Columbia; the company boasts that 50 percent of the population in the markets it serves live within two miles of a CVS store. CVS sells all sorts of general merchandise from snacks to cosmetics, but prescriptions make up approximately 70 percent of its sales, fitting for the world's largest purchaser of pharmaceuticals.