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O'Hare International Airport
Chicago's vast hub at the center of the country
O'Hare International Airport (ORD) on the northwest edge of Chicago is one of the busiest airports in the world by aircraft movements, a giant double hub for both United Airlines and American Airlines. Its central location in the heart of the country long made it the great crossroads of American aviation, the place where countless cross-country itineraries connected, and for decades it was the single busiest airport in the world.
Its odd three-letter code, ORD, comes from its origins as Orchard Field, a wartime aircraft factory site, before it was renamed for a Navy aviator hero. Because so much traffic funnels through it, O'Hare is famous as a weather-driven bottleneck: when snowstorms or thunderstorms shut it down, delays ripple out across the entire national air system. A long modernization program has been reconfiguring its runways and terminals to keep the traffic flowing.