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.
On July 1, 2010 Allegiant returned to Long Beach Airport (LGB) in Long Beach, California having previously served LGB with DC-9 jets with nonstop flights to Las Vegas (LAS) and Lake Tahoe (TVL) in 2000. The airline also intended to fly from Bellingham International Airport and Stockton several times a week; however, there is no service at present flown between these two cities although Allegiant continues to serve Stockton with flights to Las Vegas, Phoenix/Mesa and San Diego. In November 2011, Allegiant closed its Long Beach facility and consolidated all Los Angeles area flights at Los Angeles International (LAX).
In March 2010, Allegiant purchased six used Boeing 757-200 jetliners as part of plans to begin flights to Hawaii, with deliveries from early 2010 to the fourth quarter of 2011. It gained the approval for type with the FAA in July 2011, and then worked with the FAA to obtain the appropriate ETOPS rating in order to be able to serve Hawaii. Allegiant no longer operates nonstop service to Honolulu from Las Vegas.