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 (22.1m seats)
• Busiest airport: Atlanta Hartsfield-Jackson (5.4m seats)
• Busiest US domestic flight route: New York JFK to Los Angeles (310,100 seats)
• State adding most airline capacity: Illinois (+776,300 seats)

Top 10 biggest US airlines by seats

• The Big Four (American Airlines, Delta Air Lines, United Airlines, and Southwest Airlines) represent 76% share of the market in May 2026.
• American Airlines remains the biggest carrier in the US this month with 22% of the market, operating 23.2m seats.
• Delta Air Lines and Southwest Airlines represent 19% and 18% share of the market respectively, with 20.4m and 19.5m seats in May 2026.
• Spirit Airlines continues to reduce capacity, down 56% versus May 2025, equating to 2 million fewer seats.

Top 10 US airlines adding capacity year on year

• United Airlines added the most seats this month, increasing seats by 1.4m vs May 2025. Alaska Airlines made the second largest capacity increase of 1.2m seats vs last year.
• Percentage-wise, JSX increased capacity at the fastest rate of 47% vs May 2025, though the quasi-charter operator is a smaller player in the market with just 111,750 seats. Breeze Airways increased capacity by 35% year on year.
  

Top 10 busiest airline routes in the US

• The busiest airline route in the US in May 2026 is New York La Guardia to Chicago with 326,200 seats, an increase in capacity of 12% year-on-year.
• Los Angeles to San Francisco is the second busiest route with 319,000 seats, a 9% increase in capacity year on year.
• Atlanta to Fort Lauderdale made the largest percentage increase again this month of 20% vs May 2025, which equates to 43,500 additional seats.
• Capacity decreased most on the Las Vegas - Los Angeles route, declining by 18% vs May 2025.
  

Top 10 busiest US airports

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

• In May 2026, the 10 busiest airports account for 35.4% of all seat capacity in the US.
• Atlanta remains the biggest airport in capacity terms, with 5.6m seats this month, which is a 5% share of US capacity.
• Chicago O’Hare again recorded the largest capacity increase this month, adding 662,500 seats versus May 2025 to reach 5.1 million seats.
• Las Vegas decreased capacity most within the Top 10 again this month, with 319,400 fewer seats than last year. This is driven in part by the significant cuts to routes to Las Vegas made by Spirit, and the weakening of international tourism to the US.

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

• The state of Illinois added the most seats this month, with 718,000 additional seats vs May 2025. This is driven by growth at Chicago O'Hare where capacity increased by 15% year-on-year.
• The state of Florida saw the second largest increase in seats again this month, with capacity increasing by 161,500 seats vs May 2025.
• Percentage-wise capacity in Illinois increased the most, up by 12.9%. This is followed by Tennessee, where capacity increased by 4.8% this month.
• Nevada again recorded the largest capacity reduction this month, with 333,900 fewer seats, followed by California, down 221,800 seats year-on-year.
  

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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