American Airlines (AA) remains the busiest US airline this month, operating 23.15 million one‑way seats and serving major hubs like New York La Guardia (LGA) and Chicago O’Hare (ORD).
Delta Air Lines (DL) and Southwest Airlines (WN) follow closely, reflecting a competitive domestic market driven by capacity shifts.
Photo: Clément AlloingTop 10 Busiest US Airlines
The top 10 Busiest US airlines account for 91% of domestic departing seats, with legacy carriers dominating overall capacity.
According to OAG, American Airlines leads with a 21% share, followed by Delta Air Lines (19%) and Southwest Airlines (18%).
Spirit Airlines (NK) and Frontier Airlines (F9) have trimmed capacity by 28% and 12% respectively, while Allegiant Air (G4) expanded by 10% year‑on‑year.
| 1 | American Airlines (AA) | 23,150,381 |
| 2 | Delta Air Lines (DL) | 20,825,249 |
| 3 | Southwest Airlines (WN) | 20,471,652 |
| 4 | United Airlines (UA) | 17,794,487 |
| 5 | Alaska Airlines (AS) | 5,372,543 |
| 6 | JetBlue Airways (B6) | 3,642,722 |
| 7 | Spirit Airlines (NK) | 3,489,144 |
| 8 | Frontier Airlines (F9) | 3,457,098 |
| 9 | Allegiant Air (G4) | 2,419,784 |
| 10 | Hawaiian Airlines (HA) | 1,213,582 |
1. American Airlines (AA)
American Airlines maintains its position as the largest US carrier with a 21 percent market share.
Operating a fleet that spans domestic and international networks, it leverages hubs in Dallas–Fort Worth, Charlotte, and Miami to offer extensive connectivity.
2. Delta Air Lines (DL)
Delta Air Lines secures second place with 19 percent of US departing capacity. Known for its robust hub in Atlanta and a growing transcontinental network, Delta emphasizes reliability and customer experience in both domestic and global markets.
3. Southwest Airlines (WN)
Southwest Airlines, the nation’s leading low‑cost carrier, holds an 18 percent share. With a point‑to‑point model and no‑frills approach, Southwest serves over 100 US destinations, focusing on frequent flyers and leisure travelers alike.
4. United Airlines (UA)
United Airlines (UA) operates 17.8 million one‑way seats, ranking fourth. United’s hub‑and‑spoke system centers on Chicago O’Hare, Houston, and Newark, underpinning both domestic and international growth strategies.
5. Alaska Airlines (AS)
Alaska Airlines (AS), strong in the Pacific Northwest, offers 5.37 million seats. With strategic West Coast hubs in Seattle and Portland, it focuses on regional connectivity and premium onboard services.
6. JetBlue Airways (B6)
JetBlue provides 3.64 million seats, ranking sixth. The carrier differentiates itself with free in-flight entertainment and a loyal customer base, expanding beyond its New York and Boston origins.
7. Spirit Airlines (NK)
Spirit Airlines (NK), an ultra‑low‑cost carrier, holds 3.49 million seats. After reducing capacity by 28 percent amid restructuring, Spirit aims to emerge leaner, targeting price‑sensitive leisure markets.
8. Frontier Airlines (F9)
Frontier Airlines (F9) offers 3.46 million seats. Frontier’s focus on unbundled fares and secondary airports supports its low‑cost model, though capacity was trimmed by 12 percent this month.
9. Allegiant Air (G4)
Allegiant Air (G4), in ninth, provides 2.42 million seats. Specializing in underserved markets and leisure destinations, Allegiant grew capacity by 10 percent year‑on‑year.
10. Hawaiian Airlines (HA)
Hawaiian Airlines (HA) rounds out the top ten with 1.21 million seats. As the primary inter‑island and trans-Pacific carrier, it connects Hawaii to the US mainland and Asia with a focus on premium service.
Photo: American AirlinesTop 10 Airlines By Seats Added
A brief look at the top 10 carriers in the US shows the mix of full‑service and low‑cost operators competing on capacity and network breadth.
| UA | United Airlines | +1,355,443 | 8 % |
| DL | Delta Air Lines | +701,360 | 3 % |
| AA | American Airlines | +622,055 | 3 % |
| MX | Breeze Airways | +233,907 | 43 % |
| G4 | Allegiant Air | +216,014 | 10 % |
| B6 | JetBlue Airways | +179,765 | 5 % |
| HA | Hawaiian Airlines | +63,197 | 5 % |
| AS | Alaska Airlines | +52,256 | 1 % |
| Y4 | Volaris | +50,058 | 15 % |
| 4Y | Discover Airlines | +42,580 | — |
United Airlines led seat additions with 1.36 million more departures in July 2025 versus July 2024, while Breeze Airways posted the fastest growth rate at 43%.
Photo: Aero Icarus | FlickrTop 10 Busiest Routes by Seats
In July 2025, the busiest domestic route links New York La Guardia (LGA) and Chicago O’Hare (ORD) with 307,000 seats, up 6 percent from July 2024.
Los Angeles (LAX)–Chicago (ORD) saw the fastest growth at 10%, displacing several leisure markets on performance rankings.
| LGA‑ORD | New York La Guardia – Chicago O’Hare | 306,970 |
| JFK‑LAX | New York JFK – Los Angeles International | 306,621 |
| LAS‑LAX | Las Vegas – Los Angeles International | 285,056 |
| ATL‑MCO | Atlanta – Orlando International | 280,840 |
| LAX‑ORD | Los Angeles International – Chicago O’Hare | 272,607 |
| LAX‑SFO | Los Angeles International – San Francisco | 268,365 |
| HNL‑LAX | Honolulu – Los Angeles International | 259,642 |
| ANC‑SEA | Anchorage – Seattle–Tacoma International | 256,738 |
| HNL‑OGG | Honolulu – Kahului | 255,267 |
| DEN‑ORD | Denver International – Chicago O’Hare | 230,670 |
The Denver–Chicago route climbed into the top 10 this month, highlighting evolving demand patterns across key city pairs.
Photo: Aero Icarus | FlickrBottom Line
The US domestic market remains highly concentrated, with the top 10 busiest airlines supplying over 90% of departing seats and legacy airlines leading capacity growth.
The July 2025 data underscores a concentrated US market where legacy carriers lead capacity yet face nimble low‑cost competitors, and where major city‑pairs—from New York–Chicago to Los Angeles–San Francisco—drive the bulk of domestic travel demand.
Stay tuned with us. Further, follow us on social media for the latest updates.
Join us on Telegram Group for the Latest Aviation Updates. Subsequently, follow us on Google News
Top 10 Busiest US Airports in 2025, No.3 Will Surprise You!!
The post Top 10 Busiest US Airlines in July 2025: Seats, Routes, and Growth appeared first on Aviation A2Z.
