$110 Cheap United flights Sioux Falls (FSD) to St. Louis (STL)

Grab cheap round-trip United Airlines flights from $229 from FSD to STL by sorting your results from "Price (lowest to highest)" on Expedia. Or search for options from $110 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 United Airlines flights from Sioux Falls Regional Airport (FSD) to Lambert-St. Louis Intl. Airport (STL). 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 reduce 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 trips.*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.

To find the earliest departure from FSD to STL with United Airlines, filter your results by "Early Morning" and "Morning." Choosing an early flight usually means you're less likely to experience cancellations.**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.

Travel from FSD to STL with United Airlines and you'll enjoy a range of benefits including a rewarding loyalty program. When booking through Expedia as a United Mileage Plus and One Key™ member, you can also earn OneKeyCash™* to redeem on select future travel purchases.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.