Costco's history would show that the company was founded in 1976 in San Diego, California. The company headquarters is located in Washington. The company has quickly grown, and in 2012 it became the seventh largest retailer in the world, and the second largest in the United States. Costco is a warehouse shopping facility that one must become a member of in order to shop there. There are 626 stores located in several different countries around the world.