It is the third busiest airport in the world[2] by aircraft movements and the tenth busiest airport in the world by passenger traffic in 2015. It is the busiest airport in the State of Texas by both passenger enplanements and by aircraft movements (takeoffs and landings).[4] It is the tenth busiest international gateway in the United States and second busiest in Texas (behind George Bush Intercontinental Airport).[5] With nearly 900 daily flights, American Airlines at DFW is the second largest airline hub in the world and the United States, only behind Delta's Atlanta hub. Located roughly halfway between the major cities of Dallas and Fort Worth, DFW spills across portions of Dallas and Tarrant counties, and includes portions of the cities of Irving, Euless, Grapevine and Coppell.[4] It has its own post office ZIP code and United States Postal Service city designation ("DFW Airport, TX"), as well as its own police, fire protection and emergency medical services.[6] The members of the airport's board of directors are appointed by the "owner cities" of Dallas and Fort Worth, with a non-voting member chosen from the airport's four neighboring cities on a rotating basis.