O'Hare in 12 months than Ellis Island had processed in its entire existence. O'Hare remained the world's busiest airport until it was eclipsed by Hartsfield Jackson Atlanta International Airport in 1998. O'Hare had four runways in 1955; runway 14R/32L opened in 1956 and was extended to a few years later, allowing nonstops to Europe. Runway 9R/27L (now 10L/28R) opened in 1968 and runway 4R/22L in 1971. Post-deregulation developments In the 1980s, after passage of US airline deregulation, the first major change at O'Hare occurred when TWA left Chicago for St. Louis as its main mid-continent hub. Although TWA had a large hangar complex at O'Hare and had started Constellation nonstops to Paris in 1958, by the time of deregulation its operation was losing $25 million a year under competition from United and American. Northwest likewise ceded O'Hare to the competition and shifted to a Minneapolis/St. Paul and Detroit-centered network by the early 1990s after acquiring Republic Airlines in 1986. Delta maintained an O'Hare hub for some time, even commissioning a new ConcourseL in 1983. Ultimately, Delta found competing from an inferior position at O'Hare too expensive and closed its Chicago hub in the 1990s, concentrating its upper Midwest operations at Cincinnati. The dominant hubs established at O'Hare in the 1980s by United and American continue to operate today. United developed a new two-concourse Terminal1 (dubbed "The Terminal for Tomorrow"), designed by Helmut Jahn. It was built between 1985 and 1987 on the site of the original Terminal1; the structure, which includes 50 gates, is best known for its curved glass forms and the connecting underground tunnel between ConcoursesB andC. The tunnel is illuminated with a neon installation titled Sky's the Limit (1987) by Canadian artist Michael Hayden, which plays an airy, slow-tempo version of Rhapsody in Blue. American renovated and expanded its existing facilities in Terminal3 from 1987 to 1990; those renovations feature a flag-lined entrance hall to ConcoursesH/K. The demolition of the original Terminal 1 in 1984 to make way for Jahn's design forced a "temporary" relocation of international flights into facilities called "Terminal4" on the ground floor of the airport's central parking garage. International passengers were then bused to and from their aircraft. Relocation finally ended with the completion of the 21-gate International Terminal in 1993 (now called Terminal5); it contains all customs facilities. Its location, on the site of the original cargo area and east of the