Airlines increase flights at major US airport as rivalry heats up – what it means for travelers

United Airlines and American Airlines are vying for dominance at Chicago's O'Hare International Airport. Both major passenger carriers have been aggressively ramping up operations before the upcoming summer travel season.

On Tuesday, United Airlines announced that it plans to have its biggest summer at O'Hare, with a record 750 flights a day. This is about 200 more flights than its next largest competitor and the largest schedule ever flown by any airline operating at the airport, according to United.