This week in 1955, Chicago O’Hare International Airport, among the largest and busiest airports in the world, opened for commercial flights for the first time.

At the time, Chicago had become the nation’s hub for the passenger-airline industry and Midway Airport, located on the city’s South Side, had grown overwhelmed by commercial traffic. The solution was to expand O’Hare Airport.

Before O’Hare opened for commercial flights, it was used primarily as a manufacturing plant and a United States Air Force base since the mid-1940s. Originally called Douglas Field and then Orchard Place Airport, it was renamed after World War II flying ace and Congressional Medal of Honor recipient Edward “Butch” O’Hare in 1949.

By 1958, O’Hare had greatly expanded and was serving more than 10 million passengers annually. By the end of the century, that number had increased to 70 million passengers per year, making it the most congested airport in the world.

Today, O’Hare is considered as the main hub for American Airlines and United Airlines and is the sixth busiest airport in the world. It serves approximately 15.3 million passengers per year and operates a total of 585 flights per day.

O’Hare has also been chosen as the “Best Airport in North America” for ten years by two different sources namely Readers of the U.S. Edition of Business Traveler Magazine from 1998 to 2003 and Global Traveler Magazine from 2004 to 2007.

Since its first commercial flight on October 29, 1955, O’Hare has generated billions of dollars in revenue and hundreds of thousands of jobs in the region. It continues to modernize and expand; allowing Chicago and Illinois to keep drawing businesses that want to quickly access cities and markets around the globe.