Originally Posted by Trowserchilli

I think this article is telling about future bases. Specifically this paragraph:

"Philadelphia is a great success story for Frontier Airlines," said Flyr. PHL will be the fourth-largest airport station in the Frontier network this summer after Denver, Orlando, and Las Vegas, he said.

Link to SJU flying.

Frontier launches nonstop flights from PHL to San Juan, with $59 fares