19 years on: A look at the Southwest Airlines operation out of Denver airport

Since its first flight in 1971, Southwest Airlines has become one of the most popular airlines in the United States.

Known for its typically friendly staff, generally lower fares, generous checked bag policy, and lack of hidden fees, the airline has gained a loyal following from leisure and business travelers across America.

Southwest operates a point-to-point network, so it lacks the banked hubs that its full-service peers use to bolster passenger connectivity.

However, the airline has come to develop massive bases that play a significant role in connecting passengers to their final destinations. Among these bases is Denver International Airport (DEN).

The Mile High City has become the largest destination in the Southwest network. Despite its strategic importance to the low-cost carrier, Southwest has not served the Colorado capital for long. In fact, the airline just celebrated its 19th anniversary with DEN.

Southwest’s Denver operations

Today, Southwest Airlines is Denver’s second-largest carrier behind Chicago-based United Airlines. The budget carrier almost exclusively utilizes Denver’s Concourse C, though its international arrivals use Concourse A like every other Denver-bound international flight.

Southwest leases 34 gates in Denver and employs over 6,500 employees across several functional areas. At its peak, the airline has 302 daily departures from the Mile High City to 92 destinations, according to Southwest.

According to Cirium, an aviation data analytics firm, in January 2025, Southwest had 13,894 scheduled flights, equating to 2,258,778 available seats.

While this figure is impressive and the largest of any airport in the Southwest network, United Airlines boasts significantly more capacity in Denver thanks to the city’s status as one of its hubs. United will operate 29,840 flights in January 2025, offering 3,824,497 seats in total.

Though Southwest lags behind United, it has a much larger presence than Denver-based Frontier. The ultra-low-cost carrier will operate 3,370 flights this month, offering 669,772 seats.

Impressive growth in the Mile High City

Many may not realize that Southwest served Denver before its re-entry into the market in January 2006.

The airline briefly served Stapleton International Airport (Denver International Airport’s predecessor) over a decade prior to Denver’s new airport being opened.

According to the book Images of Aviation: Denver Airports From Stapleton to DIA by Jeffrey C. Price, Jeffrey S. Forrest, and Shahn G. Sederberg, Southwest entered the market in 1983 but would ultimately exit two years later.

The airline served two destinations from Denver: Phoenix and Albuquerque. The carrier cited high operating costs as part of the reason for its departure.

By 2006, however, conditions had changed. As fuel prices spiked, Southwest’s low costs were preserved by fuel hedges purchased years prior.

This gave the carrier confidence to enter more major airports. So, on January 3, 2006, Southwest initiated service to Denver International Airport with 13 daily nonstop flights to three cities: Las Vegas, Phoenix, and Chicago Midway.

The airline’s offering proved popular in the market, and it continued to expand to the robust schedule it offers today.

Even after the global pandemic in 2020, Southwest continued to grow. According to Cirium, in 2022, Southwest operated 168,841 flights from its Denver base- an increase from the previous year’s 153,652 flights. Meanwhile, in 2023, Southwest flew 194,816 Denver flights. 2024 saw that figure rise even further to 195,770 flights.

Further investments in Denver

Throughout the almost two decades Southwest has flown to Denver, it has continued to make (or attempt to make) significant investments in the Mile High City.

In 2009, eager to grow quickly in Denver, Southwest made a bid to acquire Frontier Airlines. However, the two airlines’ pilot groups failed to come to an agreement, so the potential deal was scrapped.

More recently, Southwest opened a $100 million maintenance hangar on the north end of the airport. The carrier joins Frontier and United, which have utilized maintenance bases on the airport for decades.

Beyond this, Southwest’s management team indicated that Denver could be one of the first markets where the airline rolls out its partnership with Icelandair.

As Southwest continues to evolve its business, it's clear Denver will continue to play an essential role in its operations.