The US airline industry continues to experience strong domestic travel demand, with some routes seeing significant capacity growth while a few experience reductions.
In March 2025, the busiest airline routes reflect a mix of major business corridors, leisure destinations, and airline hub connections.
Below is a list of the 10 busiest US airline routes this month, based on total seat capacity.

1. Denver (DEN) – Phoenix (PHX): 330,780 seats
The busiest US airline route in March 2025 is Denver – Phoenix, offering 330,780 seats. This represents a 5% increase compared to the same month last year.
The strong demand on this route is driven by both business and leisure travel, as Denver and Phoenix are major metropolitan areas and airline hubs. United Airlines, Southwest Airlines, and Frontier Airlines have expanded their schedules, contributing to seat growth.
With Phoenix continuing to be a popular winter escape and Denver serving as a key connection point for domestic and international flights, this route will remain one of the busiest routes in the US network.
2. Atlanta (ATL) – Orlando (MCO): 295,896 seats
The Atlanta to Orlando corridor remains a high-traffic leisure route, but capacity has decreased by 5% compared to last year.
Orlando remains a top tourist destination thanks to its world-famous theme parks and warm weather. However, airlines have slightly adjusted schedules, possibly reallocating capacity to other Florida airports.

3. Las Vegas (LAS) – Los Angeles (LAX): 293,337 seats
This high-frequency West Coast corridor continues to be in the top three busiest routes, with 293,337 seats available this month.
The LAS to LAX route remains popular among leisure travelers, particularly weekend tourists, convention attendees, and business travelers. Multiple airlines, including Southwest, Spirit, and American Airlines (AA), operate a high volume of daily flights, ensuring competitive fares.
This route continues to benefit from high demand, strategic scheduling, and strong airline competition, keeping it firmly in the top three busiest domestic routes.
4. Los Angeles (LAX) – San Francisco (SFO): 287,543 seats
The fastest-growing route on the list, Los Angeles (LAX) – San Francisco (SFO), saw a 22% capacity increase compared to March 2024.
This route has long been a critical business and commuter route, linking two of California’s largest economic hubs. The resurgence of business travel and airline competition has fueled rapid seat expansion on this route.
Multiple carriers, including United Airlines, Alaska Airlines, and Southwest Airlines, continue to offer high-frequency flights on this route, ensuring strong connectivity between Southern and Northern California.

5. Honolulu (HNL) – Kahului (OGG): 280,538 seats
Hawaii’s busiest air route between Honolulu and Kahului remains a critical link for inter-island travel, with 280,538 seats available.
Operated mainly by Hawaiian Airlines and Southwest Airlines, this short-haul route connects Oahu and Maui, serving both local residents and tourists.
Despite external challenges such as economic conditions and visitor demand fluctuations, this route remains one of the most heavily trafficked in the US, thanks to its frequency, reliability, and necessity for Hawaiian air travel.
6. New York (JFK) – Los Angeles (LAX): 269,257 seats
As the busiest transcontinental route in the US, New York JFK to LAX continues to thrive, with 269,257 seats available this month.
This route serves a diverse mix of business travelers, entertainment industry professionals, and leisure passengers. American Airlines, Delta Air Lines, JetBlue, and United Airlines (UA) offer premium transcontinental services, including flatbed business-class seats, upscale airport lounges, and frequent departures.
Despite growing competition from alternative city-pair connections, this route will continue to remain a cornerstone of US domestic aviation.

7. Denver (DEN) – Las Vegas (LAS): 249,772 seats
While still one of the busiest routes, the route between Denver and Las Vegas saw a 7% reduction in capacity compared to last year.
This route typically serves leisure and convention traffic, and the slight decrease suggests airlines are adjusting capacity based on seasonal demand trends.
8. New York (LGA) – Chicago (ORD): 245,278 seats
The New York (LGA) – Chicago (ORD) route remains a high-demand route, especially for business travelers, with 245,278 seats available.
This route is critical for corporate travel between two of the nation’s largest financial and business hubs. American Airlines, Delta Air Lines (DL), and United Airlines operate frequent flights, ensuring connectivity between LaGuardia and O’Hare.

9. Atlanta (ATL) – Fort Lauderdale (FLL): 235,393 seats
One of the few routes to see a significant drop in capacity, Atlanta (ATL) – Fort Lauderdale (FLL) is down 16% from last year, with 44,861 fewer seats.
This reduction suggests airlines are adjusting their Florida strategies, possibly reallocating flights to other markets such as Tampa or Miami. Despite this, Delta Air Lines and Southwest Airlines continue to serve this route, keeping it among the top 10 busiest.
10. Dallas (DFW) – Los Angeles (LAX): 232,186 seats
Rounding out the list is the route between Dallas and Los Angeles, with 232,186 seats available. This route serves both business and leisure travelers, connecting American Airlines’ hub at DFW with the West Coast.
Despite facing competition from direct flights to alternative airports like Orange County (SNA) and Burbank (BUR), this route remains a key transcontinental link.

Conclusion: Growth, Reductions, and Market Trends
March 2025’s busiest airline routes show continued demand for domestic air travel, with some markets expanding while others contract.
- Denver (DEN) – Phoenix (PHX) leads the list with the highest seat count.
- Los Angeles (LAX) – San Francisco (SFO) saw the fastest growth, up 22%.
- Atlanta (ATL) – Fort Lauderdale (FLL) and Denver (DEN) – Las Vegas (LAS) saw notable capacity reductions.
With airlines constantly adjusting capacity based on demand and seasonality, expect further shifts in the coming months.
Feature Image by Clément Alloing | Flickr
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