Founded in 1901, Walgreens is one of the largest drugstore chains in the United States. The company operates more than 600 drugstores in over 45 U.S. states, the District of Columbia and Puerto Rico. It provides consumer goods and medical care services, as well as operates a library that offers health-related information on topics related to stress, anxiety, allergy and depression. It also conducts health status assessments and prepares individualized care plans. The company provides clinical care and support services for patients who suffer from cancer, diabetes and strokes. Walgreens also operates an online shop that sells vitamins, supplements, electronics, toys and fitness equipment. The company maintains a presence in Houston.