United and Frontier gain DEN passengers as Southwest traffic falls

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United and Frontier gained passengers at Denver International Airport in January–July 2026 compared with the same period a year earlier, while Southwest’s total declined. Both growing airline groups also increased their share of DEN traffic, according to the July airline dashboard available through the airport’s report archive.

For airport merchants and prospective airline suppliers, the figures offer a consistent measure of changing local activity when deciding which business opportunities to investigate. Passenger growth alone does not establish higher customer spending, larger contracts or stronger profits.

A common baseline at DEN

This non-ranked watchlist includes every scheduled passenger airline group accounting for at least 5% of DEN passenger traffic in January–July 2025. It compares January 1–July 31, 2026 with the identical 2025 period, combining domestic and international traffic and regional affiliates as grouped by DEN. Geography is defined by airport operations, regardless of corporate headquarters location. Entries appear alphabetically.

The same measures apply to each: passenger counts, absolute and percentage change, and share of total DEN passengers. The baseline threshold determines inclusion regardless of whether an airline subsequently grew or declined. Smaller operators are excluded, so this is not a fastest-growing-airline ranking.

DEN’s June dashboard explains its counting definition: revenue and non-revenue passengers, inbound and outbound, based on airline submissions. These are traffic counts rather than unique customers or ticket revenue.

Three carriers, different directions

Airportwide passenger traffic reached 48,058,316 in the first seven months of 2026, compared with 47,472,439 a year earlier—a 1.2% increase. July alone declined 0.2% year over year.

• Frontier: Passengers increased from 4,223,563 in 2025 to 4,420,818 in 2026, a gain of 197,255, or 4.7%. Its reported DEN passenger share rose from 8.9% to 9.2%.
• Southwest: Passengers decreased from 13,974,007 to 13,647,728, a loss of 326,279, or 2.3%. Its reported DEN passenger share fell from 29.4% to 28.4%.
• United, including United Express: Passengers increased from 23,826,915 to 24,584,937, a gain of 758,022, or 3.2%. Its reported DEN passenger share rose from 50.2% to 51.2%.

United’s combined result requires particular care. Its mainline operation gained 954,901 passengers, while United Express lost 196,879. Using mainline growth alone would overstate the increase across the combined operation. The combined count is the consistent basis used here.

What the changes leave unresolved

The figures establish different traffic trajectories, without showing that one airline directly took customers from another. The records do not isolate how fares, flight frequency, aircraft size or connecting traffic contributed to the changes.

For all three carriers, Denver-only revenue, profit, employment and passenger spending remain unmeasured in this comparison. Southwest’s lower local count does not establish a companywide financial decline, just as Frontier’s and United’s gains do not establish higher profits. An airport merchant would still need location-specific traffic and spending evidence before translating these airportwide changes into a sales forecast.