7 Airlines: Which Carrier Dominates The Transcontinental Air Market?

The US spans the width of the North American continent, with many of its busiest cities lining opposing coasts, making transcontinental air bridges vital arteries of travel. In 2025, the global aviation market is experiencing a boom in renewed air travel demand as the lingering impact of the COVID-19 pandemic is finally shaking off. All those flyers who lost their chance during the lockdown are flocking to airports now.

A major area of the US domestic market that has boomed back into high demand is coast-to-coast flying routes. Airlines have rushed to increase capacity in the years following the end of Coronavirus restrictions. So the question is, which air carrier is the reigning champion of transcontinental itineraries over the US, today?

Thanks to the flight schedule data for October from Cirium, we can break down the roster of top airlines making the trek from the West Coast to the East Coast. An interesting result of the top-flying outfit can be one of two airlines, depending on the chosen data metric: flights or seat capacity. Either way, the numbers show two stand above the rest: Alaska Airlines with the most flights and United Airlines with the most seats available.

By The Numbers

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Alaska has absolutely blown past the rest of the field in sheer number of scheduled flights, with 30% more than United, in second, and over double the third-place contender, Delta Air Lines. However, the aircraft United selected has given it an edge, with roughly 10% more seat capacity than Alaska, despite the lower total number of scheduled flights.

Here is a table illustrating the scheduled flight data for October 2025 based on information gathered by Cirium on the “big three,” and a selection of the other top airlines in the US:

The big three all made the top four ranking, but were squarely beaten out by Alaska. United is the only one of the US’ top legacy carriers that even came close to matching Alaska’s number. JetBlue put up respectable numbers, but Frontier and Spirit made a weak showing in this ranking.

Tallying It All Up

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To add some context to the calculations used to determine “transcontinental” flights, the data reflects scheduled flights between a selection of the top hubs. The list of airports from which data were drawn is evenly split between major centers of air travel on the West Coast and the East Coast. Here is the exact roster of which airfields were considered when the scheduled data was drawn.

Naturally, California airports and the Mid-Atlantic dominate the list owing to their high share of total US flying operations. That translates directly to a high share of flights between the two coasts as well, making these hubs the perfect choices for a sampling of the most popular transcontinental itineraries.

Alaska Airlines Takes The Crown

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Perhaps coming as a surprise to some, Alaska Airlines outpaced the older and more established big three by a significant margin in flight count. The airline has consolidated its fleet down to exclusively operating the Boeing 737Next Generation and 737 MAX narrowbodies. It also has Embraer ERJ-175s, but those are only for short hops.

Alaska is doing very well in 2025, successfully bringing Hawaiian Airlines into its group and integrating a mixed fleet of Airbus and Boeing jets, including widebody aircraft. The airlines’ home turf at SeaTac has also increased capacity with the steadily improving, expanding jetliner fleet. SeaTac hosts Alaska’s busiest routes from coast to coast.

The most popular destinations outside of Seattle are New York-JFK, followed by Newark, with Boston being the third-most-frequently flown to East Coast hub. Following Seattle, the next most popular West Coast airport in the Alaska network is San Francisco, followed by Los Angeles and San Diego.

Flights in and out of the Washington, DC area are also highly popular, with connections to multiple West Coast hubs making the most popular list of transcontinental routes. The one shortfall of the strategy is the 737 family of jets, limiting the total seat capacity available. Though that did not significantly undercut the airline’s strategy, as it is only surpassed by United by 10% in that area.

United Airlines Takes Silver

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Although Alaska beat out United in departure numbers, its fleet made up for it with a larger overall seat capacity. The airline may not have the most scheduled flights overall, but it does have two of the top five most popular routes in the ranking, with its San Francisco to Newark and Los Angeles to Newark itineraries taking first and second place. These two routes alone beat the third-most-popular route by nearly double the flights and seat count.

The operations between LAX, SFO, and DC’s Dulles Airport also rank very highly in terms of traffic back and forth. Service between Boston and San Francisco is also a very popular flight route and ranks fifth among the airline’s highest-traffic transcontinental routes. United’s position as one of the premier airlines in the US and worldwide is significantly supported by these air bridges.

Today, United can proudly boast the largest fleet of commercial aircraft in the world with nearly 1,100 widebody and narrowbody airliners in its inventory. That fleet has been modernizing with new 737 MAX aircraft and 787 Dreamliner widebodies. Even though UA does not intend to purchase any 777X next-generation widebodies from Boeing at this time, the carrier is impatiently awaiting the delayed delivery of its 737 MAX 10 jets on order.

Podium Finish For Delta Air Lines

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Delta Air Lines may not have the biggest fleet in the world, but it can lay claim to the busiest mega-hub: Atlanta Hartsfield-Jackson International Airport (ATL). The fleet does number just under 1,000, which is not far behind United. Despite its enormous operations, ATL is omitted in this ranking, with the most popular flights from coast to coast being LAX, JFK, SFO, EWR, and SEA.

The number one itinerary for Delta’s transcontinental services in October 2025 is LAX to JFK, with 290 scheduled flights and over 65,000 seats available aboard those jets. San Francisco to JFK claims 201 flights with just over half the seat count, while SeaTac to JFK has a strong 124 flights and 24,000 seats available, according to the schedules. Boston and Orlando are also popular connections from LAX, with numbers close to the SEA-JFK route.

Delta’s consistently good reputation for ground and cabin service, modern lounges stocked with amenities, and excellent in-flight menu have all helped its numbers stay strong against the competition. As the 2020s march on, the airline has steadily modernized its ground-side products and its fleet of jetliners. New Airbus A321neos and A350s offer the latest technology and comfort for flyers, as well as improving airline operations.

The Honorable Mentions

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JetBlue lacks the scale of operations to contest the overall rankings against the top three operators on the list, but it can claim the third-most-popular route overall. The traffic between JFK and LAX on JetBlue’s planes racks up over 300 flights and 47,000 seats in October 2025. The carrier’s Mint suites are an especially popular premium product, featured on aircraft serving transcontinental legs.

Ranking fourth overall, American Airlines also flies the fifth-busiest air bridge from coast to coast with its JFK to LAX service. The carrier’s first class service remains a popular premium airfare option while the steadily growing 737 MAX fleet improves the comfort and enjoyment of every cabin class it carries aboard. American’s fleet outnumbers Delta’s by just over 1,000 airliners, thanks to strong performance that has enabled growth. AA has also been consistently ranked well for cabin service and in-flight dining quality.

The two low-cost carriers (LCCs) on the list did not put up significant numbers compared to the others. Considering the advantages the larger airlines have in terms of resources and established routes, it is no surprise. However, Frontier Airlines offers a great way to fly from LAX to NYC or Orlando on the cheap and Spirit Airlines likewise has highly affordable options between LAX, NYC, and Baltimore.