United Airlines and American Airlines are vying for dominance at Chicago’s O’Hare International Airport. On Tuesday, United Airlines announced that it plans to have its biggest summer at O’Hare, with a record 750 flights a day. A United Airlines airplane passes by an American Airlines plane at the O’Hare Airport in Chicago, Illinois October 2, 2014. A traveler walks though the terminal at O’Hare airport in Chicago, Tuesday, Dec. 23, 2025. Last year, the airline added service from Chicago to 29 new destinations such as Naples, Italy and St. Croix, St. Maarten.