DENVER — Frontier Airlines (F9) is doubling down on its ultra-low-cost carrier (ULCC) strategy in 2025, leaning on leisure-heavy routes, secondary airports, and frequency-driven scheduling to maximize efficiency and capture market share from legacy rivals. A look at the carrier’s 30 busiest domestic routes provides a clear window into its evolving network — one where Denver remains the heart, Orlando a rising star, and East Coast and Midwestern markets critical to its next phase of growth.
“These routes aren’t just about numbers — they’re the very building blocks of Frontier’s network strategy,” the company said in releasing the data.
Denver: The Beating Heart of the Network
Frontier’s largest base, Denver International Airport, dominates the list. Nine of the top 30 busiest routes originate from the Mile High City, led by Denver–Las Vegas, which sees an eye-popping 300 monthly flights. The corridor highlights the airline’s reliance on repeat short-haul leisure travel between two of the country’s most popular vacation destinations.
The Denver–Phoenix route is another major driver of western U.S. presence, while long-haul services to San Diego, Dallas–Fort Worth, Salt Lake City, Los Angeles, and San Francisco illustrate the breadth of Frontier’s Colorado operations. Unlike a traditional hub built for interline traffic, Denver functions as a high-turnover, origin-and-destination (O&D) hub, designed for quick turnarounds and high aircraft utilization.
Orlando Becomes a Southern Powerhouse
If Denver anchors Frontier in the West, Orlando has quickly emerged as its most important base in the Southeast. The central Florida city supports high-demand routes to San Juan, Philadelphia, Cleveland, and Cincinnati, while also enabling long-haul service. Notably, Orlando–San Juan ranks as the second-busiest route in the airline’s network.
The Orlando hub reflects intense intra-East Coast demand, with frequent flights to Atlanta, Tampa, and Baltimore. These markets combine vacation appeal with strong local demand in dense metropolitan areas where ULCC competition is limited. By building dominance in Orlando, Frontier is positioning itself at the center of a Florida battleground that remains critical for low-cost carriers.
The East Coast Connection
Frontier’s growth is increasingly visible in East Coast and Midwestern markets, particularly Philadelphia, Cleveland, and Atlanta. Philadelphia, which has steadily expanded thanks to low operating costs and access to a large population base, has become one of the airline’s most versatile hubs. Cleveland and Atlanta serve similar roles, offering strong connectivity to Florida destinations and Las Vegas.
By targeting city pairs with high O&D density and low ULCC penetration, Frontier avoids head-to-head competition in legacy hubs. Instead, it builds frequency on underserved routes, stimulating demand while keeping costs low — a hallmark of its network strategy.
High-Volume Leisure and Niche Pairings
San Juan has emerged as a surprise star in Frontier’s network. Three of its busiest routes connect the Puerto Rican capital with Orlando, Philadelphia, and New York–JFK. These long-haul leisure services carry some of the highest available seat miles (ASMs) in the network, reflecting both distance and strong load factors.
At the other end of the spectrum, short, high-turnover routes such as Las Vegas–Phoenix and Las Vegas–Ontario remain core to the ULCC model. These segments maximize utilization by moving aircraft quickly through high-demand corridors. Intra-South and intra-Florida markets like Atlanta–Tampa and Atlanta–Miami also appear in the top 30, designed to capture spillover demand during off-peak periods.
The list also highlights Frontier’s willingness to serve smaller, non-hub cities such as Cincinnati, Salt Lake City, and San Diego. By entering underserved markets with low fares, Frontier carves out niches overlooked by larger carriers.
Bottom Line
Frontier’s busiest routes paint a clear picture of its strategy for 2025: volume-driven, leisure-focused, and built around secondary airports where it can compete on price and frequency without the overhead of legacy hubs. Whether anchored in Denver or Orlando, or spreading east through Philadelphia and Cleveland, the airline’s network is tuned for utilization and cost discipline.
“These markets are not just busy; they are hand-crafted to accommodate a business model that favors volume, utilization, and demand-responsive scheduling,” Frontier said.
The carrier acknowledged that its list of top routes will evolve as demand shifts and competition intensifies. But for now, these 30 markets reveal how Frontier is betting its future: on affordable fares, lean operations, and a calculated focus on America’s leisure travel corridors.
