$126 Cheap American Airlines flights St. Louis (STL) to Washington (IAD)

You can find affordable round-trip American Airlines flights from $251 from STL to IAD by sorting your results from "Price (lowest to highest)" on Expedia. Or look for bargains from $126 for a one-way trip.**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 before your departure to find cheaper fares on American Airlines flights from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD). You can save 25% by booking your domestic flight 34 to 86 days in advance compared to 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 your timing spot on, 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.

Search American Airlines's earliest flights from STL to IAD by selecting our "Morning" and "Early Morning" filters. Not only will you get to your destination sooner, early departures also have a 20% less chance of being canceled.**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.