This figure does not include the numerous vehicles and personnel used by contractors. The USPS is the operator of the largest civilian vehicle fleet in the world.[2] The USPS is legally obligated to serve all Americans, regardless of geography, at uniform price and quality. The USPS has exclusive access to letter boxes marked "U.S. Mail" and personal letterboxes in the United States, but now has to compete against private package delivery services, such as United Parcel Service, FedEx, and Amazon.[5]