O'Hare International Airport (ORD) is the main airport serving Chicago Illinois, and one of two airports in the city (the other being Midway International Airport). The airport is commonly referred to as "Chicago O'Hare". It is the busier of the two, and is a hub for both American Airlines and United Airlines, the latter of which is headquartered in Chicago.
The airport is very large, and has the most amount of runways in a single airport, at eight. It has four terminals (1, 2, 3, and 5) connected by a peoplemover. It was the busiest airport in the world from 1963 to 1998, when Hartsfield-Jackson International Airport in Atlanta, Georgia became busier.
- Terminal 1 consists of concourses B and C, and was designed by Helmut Jahn. It was built in the 1980s. It is United's terminal.
- Terminal 2 consists of concourses E and F, and was designed by Charles F. Murphy. It was built in the 1960s. It is Delta Air Lines's terminal, and is also used by Air Canada among other Canadian carriers.
- Terminal 3 consists of concourses G, H, K, and L. Like Terminal 2, it was built in the 1960s and was designed by Charles F. Murphy. It is American's terminal.
- Terminal 5 consists of concourse M. It was built in 1993 and is the international terminal.