Fly nonstop from Chicago to Philadelphia for $98 round-trip as part of the previously mentioned sale from Frontier.
This is a new nonstop route from Frontier with flights set to begin on March 13. The above fare is valid for travel on Tuesdays, Wednesdays, and Saturdays, through May 13.
Searching FlyFrontier.com, we found seats departing ORD on Tuesday, March 17, returning from PHL on the following Tuesday, March 24.
For booking info, see our Fare Details.