List of Top 9 U.S. Airlines by Size, #5 Will Surprise You!

Top 9 U.S. Airlines by Size: The U.S. aviation industry is entering a historic phase of transformation and 2025 is proving to be a landmark year. In a major milestone for American air travel, Alaska Airlines has officially received a single operating certificate (SOC) from the Federal Aviation Administration (FAA). This marks its regulatory integration with Hawaiian Airlines.

This is audio of Hawaiian Airlines flight HAL866 — the final flight ever to use the “Hawaiian” callsign and ICAO identifier. 🌺✈️
After 95 years of independence, Hawaiian has officially merged with Alaska Airlines. From now on, all flights will operate under the Alaska “AS” code. pic.twitter.com/yb3oKqGpQ3

— Turbine Traveller (@Turbinetraveler) October 29, 2025

According to Ben Minicucci, President and CEO of Alaska Air Group, this achievement “marks an important step in our journey as a combined organisation.” The move strengthens the group’s Pacific presence, connecting over 140 destinations across North America, Latin America, Asia, and the Pacific with Europe expansion plans on the horizon for 2026.

This development highlights how U.S. airlines continue to evolve through mergers, digital innovation, and global route expansion. Whether it’s Delta Air Lines’ international dominance or Southwest’s unmatched domestic network, each carrier is known for sustainability, connectivity, and passenger experience. Let us explore top 9 U.S. airlines by size and fleet. 

List of Top 9 U.S. Airlines by Size, #5 Will Surprise You!

From global carriers like Delta, American, and United to the ultra-low-cost pioneers Spirit and Frontier, here is an overview of the top 9 airlines in the United States ranked by size, fleet, and destination reach:

Here are the top 9 Airlines by size in the U.S.: 

1. Delta Air Lines

Delta Airlines continues to dominate as one of the most reliable U.S. carriers, with a strong focus on sustainability and cutting-edge in-flight experience. It operates with major hubs in Atlanta, Detroit, and Minneapolis. Its expansion in transatlantic routes and SkyMiles loyalty upgrades have cemented its leadership globally.

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2. American Airlines

Known for its expansive network and Oneworld alliance benefits, American remains a major player in U.S. and international travel. It is headquartered in Fort Worth, Texas, and is known for digital check-in improvements and renewed business-class offerings are setting high benchmarks.

3. United Airlines

With sustainability at its core, United’s efforts in sustainable aviation fuel (SAF) and electric aircraft partnerships have made it one of the most forward-looking airlines in the U.S. It has major hubs in Chicago, Denver, and Houston.

4. Southwest Airlines

The Southwest Airlines is a very beloved one for its no-change-fee policy and strong domestic connectivity. It is renowned for point-to-point routes and a no-change-fee policy. Hence, Southwest maintains its reputation for affordability and reliability, especially across U.S. leisure routes.

5. Alaska Airlines + Hawaiian Airlines (The Integration Milestone)

Here’s where things get surprising: 

Alaska Airlines has officially received a single operating certificate from the FAA, which allows it to operate alongside Hawaiian Airlines under a unified regulatory framework while maintaining both brands. Because of this integration, and combination, thousands of hours of coordination in training, safety protocols, and operations are represented. 

However, Passengers won’t see major changes yet both airlines will retain their distinct branding and hospitality. In addition, starting next spring, a unified passenger service system (PSS) will make booking and travel even more seamless across both carriers.

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Conclusion 

Therefore, from the Delta powerhouse to the newly unified Alaska–Hawaiian operation, these airlines are a true example of resilience and innovation of the U.S. aviation sector. Moreover, the Alaska–Hawaiian SOC milestone, in particular, symbolises a major regulatory and operational triumph for the U.S. As American skies evolve, one thing is clear that 2025 will be remembered as the year when U.S. airlines truly took flight into a more integrated and connected future.

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