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.
The company had charter contracts with Caesars Entertainment to ferry customers to Caesars casino properties through Reno-Tahoe International Airport, Laughlin/Bullhead International Airport and Tunica Municipal Airport. These contracts ended in December 2012 when Caesars Entertainment signed a new contract with Republic Airways to provide the charter service to Caesars properties in Atlantic City, New Jersey, Tunica, Mississippi and Laughlin, Nevada.
In the fall of 2001, Allegiant exited bankruptcy and the case was officially closed in early 2002. In March 2002, Allegiant entered into a long-term contract with Harrah's to provide charter services to its casinos in Laughlin and Reno, Nevada. At the same time, the airline acquired its first McDonnell Douglas MD-80 jetliner. From 2002 through 2004, the airline developed its scheduled-service business model. By 2004, Allegiant was flying from 13 small cities to Las Vegas offering bundled air and hotel packages.
In May 2017, Allegiant Air took delivery of its first brand-new A320. Allegiant took delivery of ten new A320s in 2017 and is scheduled to accept two in 2018. All new aircraft will be painted in Allegiant's new livery at the time it is delivered. Older Airbus aircraft will be repainted during their C-checks. The new Airbus aircraft will have fuel-efficient sharklets. The new A320s seat 186 passengers, an increase of the 177 seats that are found in the rest of the Allegiant A320 fleet. To fit the additional nine seats, Allegiant opted for the Airbus Space-Flex V2 Lavatory. 
The bankruptcy allowed Maurice J. Gallagher Jr., one of the airline's major creditors, to gain control of the business. A veteran leader of low-cost airlines, Gallagher had worked with WestAir and as CEO of ValuJet Airlines. In June 2001, Gallagher restructured Allegiant to a low-cost model, focusing on smaller markets that larger airlines did not serve with mainline aircraft. Allegiant's headquarters and operations were also moved to Las Vegas.
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).