Allegiant Air is a major American airline headquartered in Summerlin, Nevada, a suburb of Las Vegas. The airline focuses on serving leisure traffic from small and medium-sized cities which it considers to be underserved, using a ultra low-cost business model with minimal inclusions in fares and a greater number of add-on fees.

WestAir Commuter Airlines, was a U.S.-based regional airline formed when Stol Air Commuter changed its name in 1978 to WestAir Airlines; it was renamed WestAir Commuter Airlines in 1986. One of the founders was Maurice J. Gallagher, Jr., who later acquired Allegiant Air. WestAir subsequently became a United Express air carrier via a code sharing agreement with United Airlines. It was headquartered in Fresno, California and was controlled by WestAir Holding, Inc. WestAir was sold to Mesa Air Group in 1992.