Chicago O'Hare International Airport (IATA: ORD, ICAO: KORD, FAA LID: ORD), also known as O'Hare Airport, O'Hare Field, Chicago International Airport, or simply O'Hare, is an international airport located on the Far Northwest Side of Chicago, Illinois, 17 miles (27 km) northwest of the Loop. It is the primary airport serving the Chicago area, with Midway Airport, about 10 miles (16 km) closer to the Loop, serving as a secondary airport..

O'Hare is the busiest airport in the world by number of takeoffs and landings, a title it reclaimed in 2014, beating out Hartsfield-Jackson Atlanta International Airport (which had the title from 2005-2013). Until 1998, O'Hare was also the busiest airport in the world in number of passengers. It was surpassed mainly due to limits imposed on the airport by the federal government to reduce flight delays. As of 2014, O'Hare is the third busiest airport in the United States and sixth busiest in the world by passenger traffic.