Alaska Air Group, Inc. is the holding company of Alaska Airlines, Inc. (Alaska) and Horizon Air Industries, Inc. (Horizon), which together with its partner regional airlines, serve approximately 100 cities through a network in Alaska, the Lower 48, Hawaii, Canada and Mexico. The Company operates in three segments: Alaska Mainline, which is the Boeing 737 part of Alaska's business; Alaska Regional, which is Alaska's shorter distance network, and Horizon, which operates regional aircraft. It operates two airlines: Alaska Airlines and Horizon Air. Alaska operates a fleet of passenger jets (mainline) and contracts with Horizon, SkyWest Airlines, Inc. (SkyWest) and Peninsula Airways, Inc. (PenAir) for regional capacity under which Alaska receives all passenger revenue from those flights.. Horizon operates a fleet of turboprop aircraft and sells all of its capacity to Alaska.