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.
At 19″ wide, the middle seats in the airline's Airbus 321s, A320s, and A319s are wider than the window and aisle seats and, as of July 2015 when the airline began installing them, are the widest middle seats of any airline in the U.S. The A321ceo and A321neo, utilized on longer flights, features industry-standard seat pitch of 30"-32". The airline uses a seat pitch of only 28″-29", the tightest seat pitch of any airline in the United States, on their A320ceo and A320neo, typically operated on shorter flights. Frontier Airlines has 28"-31" on the Airbus A319, which they are phasing out. Main cabin seats are "pre-reclined" by the airline and there are no televisions mounted at any of the seats in order to save weight.
Chautauqua Airlines operated up to 12 Embraer 135 and 145 jets out of Milwaukee. Frontier began branding these flights as Frontier Express in the spring of 2011. With the pull-down of the Milwaukee hub, the only route that continued to operate with a Frontier Express ERJ-145 jet was Milwaukee to Rhinelander. However, Frontier service to Rhinelander ended on January 3, 2013, and Chautauqua transferred the remaining aircraft to other partners.
In February 2015, Frontier announced that they will begin service to several destinations from Atlanta adding the airport as a focus city. In July, Frontier also began decreasing service from Washington Dulles International Airport removing the airport as a focus city. In early 2016 Frontier announced major route expansion from airports nationwide including Atlanta, Chicago, Cincinnati, Cleveland, Orlando, and Philadelphia. In June 2016, Frontier re-established service to Port Columbus International Airport. In May 2017, the airline announced opening a new crew base in Las Vegas in the fall 2017 to improve operational reliability and potentially create new jobs in Las Vegas. In December 2017, Frontier began service to Buffalo, New York, with service to Denver, Colorado, and Florida, including Miami, Fort Myers, Orlando, and Tampa.
In April 2013, Frontier introduced a modified version of that livery, keeping the iconic animals on aircraft tails, but dropping its former slogan and replacing "FRONTIER" with "FLYFRONTIER.COM", the company's website, in support of new marketing that focused heavily on the airline's web presence. This livery was only painted on a few newly delivered aircraft. Aircraft in the older livery received "FLYFRONTIER.COM" titles on engine nacelles.
Today, it serves 77 cities on 176 routes. They cover destinations like Bellingham, Washington, Vancouver, British Columbia, Fort Lauderdale, Las Vegas, Nevada, Los Angeles, California, Myrtle Beach, Orlando, PhoenixMesa, Arizona, San Francisco Bay, Fort Myers and Tampa Bay or St. Petersburg-Clearwater. They have their operation bases at Bellingham International Airport, Fort Lauderdale-Hollywood International Airport, Las Vegas McCarran International Airport, Los Angeles International Airport, Oakland International Airport, Orlando-Sanford International Airport, PhoenixMesa Gateway Airport and St. Petersburg-Clearwater International Airport.