In 1997, Maverick Airways was operating code share service for Frontier with de Havilland Canada DHC-7 Dash 7 STOL capable turboprops between Denver (DEN) and two destinations in Colorado: Grand Junction (GJT) and Steamboat Springs (SBS). However, the service was short lived as Maverick encountered financial challenges and then ceased all flights.
On October 25, 2007, the airline opened a fourth focus city and operations base at Phoenix-Mesa Gateway Airport in Mesa, Arizona, connecting 13 cities already served by Allegiant and one new city to the Phoenix metropolitan area. The airport announced a 10,000-square-foot (930 m2) expansion in August 2008, which increased the number of gates from two to four and allowed Allegiant to triple the number of flights from Phoenix. The expansion was funded by a loan from Allegiant which will be repaid by passenger fees.
At the checkin there was a male and I am assuming he was from Jamaica who was very impatient with us. We had even got our bags to the checkin before he was asking for our boarding passes and I’d cards. He stated that the boarding passes we had (which we printed the day before) would not work and through our boarding passes in the trash and after we presented our I’d cards proceeded to print out new boarding passes and our baggage claim tickets.
For many years, analysts had predicted that jetBlue's growth rate would become unsustainable. Despite this, the airline continued to add planes and routes to the fleet at a brisk pace. In addition in 2006, the IAM (International Association of Machinists) attempted to unionize JetBlue's "ramp service workers", in a move that was described by JetBlue's COO Dave Barger as "pretty hypocritical", as the IAM opposed jetBlue's creation when it was founded as New Air in 1998. The union organizing petition was dismissed by the National Mediation Board because fewer than 35 percent of eligible employees supported an election.
On October 22, 2008, jetBlue opened its new primary hub at John F. Kennedy International Airport (JFK), Terminal 5, or simply T5. The mostly new terminal, costing approximately $800 million, partially encircles the historic TWA Flight Center, the former Trans World Airlines terminal designed by Eero Saarinen, which remains closed. According to the plan, passengers will eventually be able to check in for flights in the landmark building, then transfer to the new structure via the original passenger departing-arrival tubes from Saarinen's original terminal and its 1969 addition by Roche-Dinkeloo.
In late 2009 Republic began to consolidate administrative positions and moved 140 jobs from the Frontier Airlines Denver headquarters to Indianapolis, Indiana. Shortly after that, in January 2010, Republic Airways announced that it would move all of its executives to Indianapolis. In February the Denver Business Journal stated that the headquarters would be moved "soon". Despite this, according to the Denver Business Journal, Frontier Airlines will still maintain a local headquarters in Denver to house Training, Marketing, Customer Reservations, and Scheduling & Planning teams after extending its lease on the building through 2020.
The initial JetExpress partnership with Mesa ended in January 2004, when Horizon Air was selected to operate the routes. Horizon utilized slightly larger CRJ-700 regional jet aircraft on these routes. In August 2006, Frontier and Horizon ended their partnership. While Frontier was generally pleased with Horizon's operation, the carrier decided that it needed to revisit the agreement and find a provider with additional regional jets to grow the operation. The last of the CRJ-700's was returned to the Horizon Air fleet on November 30, 2007.