Alaska Air Group Inc operates an airline network in the United States (extensively in Alaska), Canada, Mexico, and other regions. With two subsidiaries, Alaska Airlines and Horizon Air, it has established an expansive network, with the majority of revenue generated by transporting passengers. The company has multiple agreements with other airlines to address specific needs, such as frequent-flier programs and joint itineraries. It reports in three operating segments: Alaska mainline (approximately three fourths of revenue), Alaska regional, and Horizon. Majority of its business is conducted in the northwestern part of the United States. Its Seattle hub accounts for approximately half of total passengers.