Controversial plans to expand Chicago O’Hare Airport would add an additional runway and reconfigure the seven existing runways. The proposed expansion would allow the airport to handle 1.6 million flights annually, up from approximately 928,000 in 2003. O’Hare is not alone in having expansion plans: 18 of the 31 large hub airports in the U.S. are planning to add runways in the next decade. As of 2001, these 31 airports accounted for 70 percent of U.S. air passengers, and the top 25 of these airports accounted for 86 percent of all severe air traffic delays. However, neighboring communities often oppose airport expansions, and the O’Hare expansion plans are particularly controversial. O’Hare is surrounded by a densely populated ring of suburban municipalities whose residents already complain about the noise generated by flights in and out of O’Hare.