US aviation market data

US aviation market at a glance

Here are some highlights from this month's US market data:

• Largest airline: American Airlines (22.9m seats)
• Busiest airport: Atlanta Hartsfield-Jackson (5.4m seats)
• Busiest US domestic flight route:  Los Angeles to San Francisco (328,600 seats)
• State adding most airline capacity: Illinois (+267,100 seats)

Top 10 biggest US airlines by seats

• American Airlines remains the biggest carrier in the US this month with 22% of the market, operating 22.9m seats.
• Delta Air Lines and SouthWest Airlines represent 19% and 18% share of the market respectively, with 20m and 19.6m seats in June 26.
• Spirit Airlines ceased operations on May 2, taking 3.5m seats out of the market vs last year.  
•   The Big 4 carriers continue to represent 76% share of the market.                                                    

Top 10 US airlines adding capacity year on year

• Alaska Airlines added the most seats this month, increasing seats by 1.23m vs June 25 - an increase of 24% year on year.   United Airlines made the second largest capacity increase of 1.19m seats vs last year.
• Percentage wise Breeze Airways increased capacity at the fastest rate of 27% vs June 25, followed by Volaris and Frontier Airlines which increased capacity by 22% and 21% respectively. Frontier Airlines, in particular, adding capacity on former Spirit routes.

Top 10 busiest airline routes in the US

• The busiest route this month is Los Angeles to San Francisco with 328,600 seats, an increase in capacity of 21% vs June 25, equivalent to 56,200 additional seats. 
• New York La Guardia to Chicago is the second busiest route with 311,300 seats, a 6% increase in capacity year on year.
• Boston to Chicago also sees a double digit percentage increase this month of 19% vs June 25, which is an additional 37,900 seats.
• Capacity decreased most on the Atlanta to Orlando route, declining by 9% vs June 25.  Followed by Los Angeles to Chicago reducing by 6% vs last year.

Top 10 busiest US airports

Top 10 airports by departing seats (one-way) this month 

• The Top 10 busiest airports continue to account for 35.6% of capacity. 
• Atlanta remains the biggest airport in capacity terms, with 5.4m seats,  despite a reduction of 176,200 seats.
• Chicago O'Hare saw the largest increase in capacity again this month, adding 286,000 more seats vs June 25  to 4.9m seats. 
• New York JFK decreased capacity most within the Top 10 this month, with 179,200 fewer seats than last year.  
• Charlotte Douglas International also saw a significant reduction in capacity, down by 176,600 seats.

US states adding & removing most capacity this month vs same month last year

• The state of Illinois continued to add the most seats this month, with 267,100 additional seats vs June 25.  
• Percentage wise capacity in Pennsylvania increased at the fastest rate, up 5.3%, 132,600 additional seats.
• Capacity decreased most in Florida this month, by 563,500 seats. This reflects the collapse of Spirit Airlines, which was heavily concentrated in the state and the broader weakness in the ultra-low-cost airline sector with higher operating costs in 2026

Total US flight capacity by month, domestic & international

To view US flight capacity statistics from 2019-2026, click the button below to download the data.

*As of July 2025, international capacity is reported on a two-way basis (previously one-way departing).

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