For years, Hartsfield-Jackson Atlanta International Airport has held the title of the world’s busiest airport. Aside from 2020, when passenger traffic fell sharply due to the COVID-19 pandemic, the airport has ranked first every year since 1998. Even last year, Atlanta retained that position, offering around 63.1 million seats. However, that long-standing dominance is set to change in 2026.

According to scheduled data from aviation analytics provider Cirium, Chicago O’Hare International Airport is set to handle the highest number of scheduled flights during H1 2026. The airport has approximately 218,700 one-way flights scheduled over the period (around 437,000 total movements), compared with roughly 389,600 scheduled flights at Atlanta.

Chicago O’Hare International Airport Takes The Lead

Chicago’s lead is also notable in year-on-year terms. In fact, the airport is scheduled to handle more flights in H1 2026 than Atlanta did during the same period last year. The latter recorded around 387,000 scheduled flights in the first half of 2025, while Chicago O’Hare is set to exceed that figure this year. Compared with its own H1 2025 schedule, when O’Hare handled approximately 386,300 flights, the airport’s current schedule represents growth of around 13%.

This makes it the fastest-growing US airport by scheduled aircraft movements in H1 2026. Furthermore, Atlanta ranks second by flight volume in H1 2026. Detroit Metropolitan Wayne County Airport follows in third place, with around 76,900 flights scheduled, reflecting year-on-year growth of about 4%. It is worth noting that Chicago O’Hare’s lead is based on aircraft movements. When measured by passenger volume, Atlanta still remains the busiest airport in the United States.

Chicago O’Hare’s Growth Is Driven By American Airlines And United Airlines

Chicago’s lead reflects a steady growth over several years rather than a single jump. Since 2020, the airport has seen flight volumes increase by more than 50%, alongside a significant increase in overall seat capacity. Indeed, the change has largely been driven by expansion from its two main hub carriers, American Airlines and United Airlines. According to Cirium data, the oneworld alliance member is operating around 22.1% more flights from Chicago O’Hare in H1 2026 compared with the same period last year.

Chicago has long been a core hub for the airline, since 1926, when it launched its Chicago–St. Louis route. Today, it serves more than 180 destinations from the airport. In 2025 alone, it added 29 new routes, including a new transatlantic service to Naples. More recently, American announced two new year-round daily routes to Allentown and Columbia, along with a seasonal daily service to Kahului, Hawaii. Besides, United has also continued to grow aggressively at O’Hare.

In H1 2026, the carrier is offering around 12.1% more flights year-on-year. It has announced several new and returning routes from the airport, including the resumption of service to Erie and new flights to Tri-Cities, Santa Barbara, and Monterey. So far this year, the Star Alliance member has unveiled more than 13 new destinations from the airport. Indeed, this expansion has been supported by the additional five gates that the airline secured last year. The gates also enabled the carrier to reinstate service to Tel Aviv for the first time since 2023.

Why Atlanta Still Leads By Seats Despite Fewer Flights

As noted earlier, Chicago O’Hare leads the US by flight volume in the first half of 2026. However, when measured by passenger capacity, Atlanta remains firmly in the top position. According to Cirium data, the airport is offering approximately 31.1 million seats during the period, compared with around 26.7 million seats at O’Hare.

The difference largely comes down to aircraft mix. A significant share of Chicago’s flights are operated by regional aircraft as the airport is a major connecting hub for both United and American’s regional traffic. Of the roughly 218,700 flights scheduled at O’Hare in H1 2026, about 106,900, around 49%, are planned to be operated by regional jets.

Meanwhile, Atlanta’s schedule looks very different. Of the airport’s roughly 194,900 scheduled flights, only around 25,900, or about 13%, are operated by regional aircraft. Instead, the airport sees much heavier use of mainline narrowbody aircraft. Approximately 158,800 flights in H1 2026 are scheduled on mainline narrowbodies, accounting for around 26.5 million seats.