American Airlines & United’s capacity war at Chicago-O’Hare pushes the airport to 8th busiest globally
Since 2021, United Airlines has kept adding more seats to its network at Chicago-O'Hare, while at one point, American Airlines removed some capacity from the airport.
The capacity war between American Airlines and United Airlines at Chicago O’Hare International Airport (ORD) has resulted in the airport ranking as the eighth busiest in the world in 2025, according to recent data released by OAG.
On January 16, OAG issued its report about the busiest airports in the world in 2025. While there were few surprises, with Hartsfield-Jackson Atlanta International Airport (ATL) still ranking first, the rise of ORD in the rankings was curious.
In 2024, ORD was the 10th busiest airport globally, with 46.9 million departing seats, still behind its pre-pandemic peak of 50.55 million departing seats in 2019. In 2025, the airport moved up to the eighth spot and surpassed its 2019 capacity with 50.58 million departing seats.
One of the reasons for ORD’s capacity growth is American Airlines and United Airlines (re)newed focus on the airport. Cirium’s Diio Mi shows that the two airlines added 2.2 million and 1.8 million additional seats, respectively, compared to 2024, with the airport’s total seats growing by 3.5 million year-on-year (YoY).
After the worst of the pandemic in 2020, both airlines began rebuilding their networks in 2021, including at ORD. However, United Airlines saw an opportunity to grow at the airport, while American Airlines was focused elsewhere across the country. The latter’s seat capacity at ORD actually shrank between 2022 and 2023.
Meanwhile, United Airlines’ market share at the airport kept growing, and American Airlines is now playing catch-up.
During American Airlines' Q3 2025 earnings call on October 23, 2025, Robert Isom, the Chief Executive Officer (CEO) of the airline, detailed that the airline already has Dallas/Fort Worth International Airport (DFW) and Charlotte Douglas International Airport (CLT) “appropriately sized.”
Now, its focus is on building capacity at ORD and crossing the 500-per-day departure mark in 2026.
In September 2025, Scott Kirby, the CEO of United Airlines, estimated that American Airlines was losing around $800 million a year at ORD.
Nevertheless, according to currently published schedules, both airlines will continue to grow at ORD in 2026. American Airlines’ seat capacity at ORD is up 15% YoY, while United Airlines’ scheduled seat capacity is up 9% YoY.
Rytis Beresnevicius
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