$155 Cheap American Airlines flights St. Louis (STL) to Billings (BIL)

Apply the "Price (lowest to highest)" filter on Expedia to search for cheap American Airlines return flights from $276 from STL to BIL. Affordable one-way fares from $155 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.

Start searching one to three months ahead of your travel date to find cheap fares on American Airlines flights from Lambert-St. Louis Intl. Airport (STL) to Logan Intl. Airport (BIL). You can save 25% by booking your domestic flight 34 to 86 days in advance versus last-minute reservations made 6 to 12 days out. You could also cut costs by buying your fare on a Sunday, as it's 6% cheaper on average than a Monday, the most expensive day to book.* Get the timing right, and you can enjoy significant savings on domestic flights.*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 "Morning" and "Early Morning" to browse the earliest departures from STL to BIL. Setting 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.