$89 Cheap American Airlines flights St. Louis (STL) to Denver (DEN)

Apply the "Price (lowest to highest)" filter on Expedia to search for cheap American Airlines return flights from $177 from STL to DEN. Affordable one-way tickets from $89 are available as well.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

For cheap American Airlines fares from Lambert-St. Louis Intl. Airport (STL) to Denver Intl. Airport (DEN), start searching one to three months before your intended departure. Reserving domestic flights 34 to 86 days in advance could save you 25% compared to booking just 6 to 12 days ahead. The day you book can also affect the price you pay. Sunday is usually the most affordable, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking your journey on a Sunday.**Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC's global airline sales database.

Sort your results by "Early Morning" and "Morning" to browse the earliest flights from STL to DEN. Taking off early means flight cancellations are less likely.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.