$216 Cheap United flights Philadelphia (PHL) to Rapid City (RAP)

Scoring cheap one-way United Airlines flights from PHL to RAP from $216 on Expedia is easy — just filter by "Price (lowest to highest)." Alternatively, check out our budget-friendly return fares from $285 for your next exciting adventure.**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 United Airlines fares from Philadelphia Intl. Airport (PHL) to Rapid City Regional Airport (RAP), start searching one to three months before your planned 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 overall cost. 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 trip 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.

To find the earliest departures from PHL to RAP with United Airlines, filter your search by "Morning" and "Early Morning." Choosing an early flight generally 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.

With a rewarding loyalty program, United Airlines is a favorite of many travelers journeying from PHL to RAP. Plus, as a United Mileage Plus and One Key™ member booking through Expedia, you could earn OneKeyCash™* on eligible flights on top of your airline miles.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.