The Walgreen Company (Walgreens) is the largest drug retailing chain in the United States. As of May 31, 2014, the company operated 8,217 stores in all 50 states, the District of Columbia, Puerto Rico and the U.S. Virgin Islands. It was founded in Chicago, Illinois, in 1901. The Walgreens headquarters office is in the Chicago suburb of Deerfield, Illinois.
In 2014, the company agreed to purchase the remaining 55% of Switzerland-based Alliance Boots that it did not already own to form a global business. Under the terms of the purchase, the two companies merged to form a new holding company, Walgreens Boots Alliance Inc., on December 31, 2014. Walgreens became a subsidiary of the new company, which retains its Deerfield headquarters and trades on the Nasdaq under the symbol WBA.