Designed to be the successor to Chicago’s “busiest square mile in the world”, O’Hare began as an airfield serving a Douglas manufacturing plant for C-54 military transports during World War II. It was named after Edward “Butch” O’Hare, the U.S. Navy’s first Medal of Honor recipient during that war. As the first major airport planned after World War II, O’Hare’s innovative design pioneered concepts such as concourses, direct highway access to the terminal, jet bridges, and underground refueling systems.
O’Hare became famous as the first World’s Busiest Airport of the jet age, holding that distinction from 1963 to 1998; today, it is the world’s sixth-busiest airport, serving 83 million passengers in 2018. In 2019, O’Hare had 919,704 aircraft operations, averaging 2,520 per day, the most of any airport in the world in part because of a large number of regional flights. O’Hare serves as a major hub for both United Airlines (which is headquartered in Willis Tower) and American Airlines. It is also a focus city for Frontier Airlines and Spirit Airlines.