US Aviation Market Data Insights

Find answers to your questions about the US aviation market, with flight data insights and analysis powered by OAG's Schedules Analyser.

• Which are the top airlines in the USA?
• What's the country's busiest airport?
• Which US domestic flight route is busiest?
• Is there more domestic or international capacity in the US aviation market?
• Exclusively available to download: US monthly airline seats data from 2019-present day.

The data is updated monthly. Seats are calculated as departing seats (one-way).

• American Airlines remains the biggest carrier in the US in October 2025, holding a 21% share of the market with 22 million available seats.
• Delta Air Lines and Southwest Airlines each hold a 19% market share in October 2025, with 19.8 million and 19.7 million available seats, respectively.
• Spirit Airlines decreased capacity by 30% compared to October 2024, with 1.2m fewer seats. 
• Frontier Airlines and JetBlue Airways reduced capacity by 2%.
• The "Big Four" - Delta, American, United, and Southwest Airlines - continue to represent a 75% share of the market.
                                                     
• 
• 

• United Airlines led seat growth again this month, adding 757,600 more seats compared to October 2024. Southwest Airlines also increased capacity by 550,700 seats.
  
• Breeze Airways saw the fastest growth in capacity, up by 48%, while Avianca followed with a 25% increase.

• The busiest route again this month is New York La Guardia to Chicago with 319,700 seats, an increase of 13% capacity vs October 2024.
• Capacity decreased most on the Las Vegas - Los Angeles route by 13%, followed by the Honolulu - Kahului route by 12% vs October 2024. 
  
• The Denver - Las Vegas route moved from 16th to 10th place, displacing Los Angeles to Chicago from the Top 10 busiest routes.

• The state of Illinois saw the largest increase in seats again this month, with capacity increasing by 427,700 seats vs October 2024.
• Tennessee saw the largest percentage increase in capacity this month, up 12%, led by strong growth in Nashville - including two new international routes to Reykjavik and Dublin - as well as growth from domestic feeder routes.
• Capacity decreased most in Nevada this month, by 318,200 seats, followed by North Carolina with 193,500 fewer seats vs last year.

To view US flight capacity statistics from 2019-2025, 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).