How it started
History
Major airlines in the United States had long maintained relationships with regional carriers which fed passengers from small markets to larger cities. The Airline Deregulation Act of 1978 spurred industry consolidation, and as the hub system became more pronounced, airlines formalized these relationships through code sharing, co-branding and listing regional partners' flights in computer reservations systems.
On May 1, 1985, United formally partnered with Air Wisconsin, Horizon Air, and WestAir as United Express, feeding its hubs at Chicago–O'Hare, Seattle/Tacoma, and San Francisco, respectively. Aspen Airways joined in 1986 the hub at Denver–Stapleton. Horizon Air was bought by Alaska Airlines in 1987 at which time Horizon's contract with United was cancelled and a new carrier, North Pacific Airlines (NPA), was established by WestAir to service the Seattle hub as well as hubs at Portland, Spokane, and Boise. Aspen was dismantled in 1990 being sold to Air Wisconsin and Mesa Airlines. NPA was merged into its parent, WestAir, in 1991. San Juan Airlines of Seattle and SouthCentral Air of Anchorage, Alaska, also operated as United Express from 1987 through 1989.
In 1988, Presidential Airways became a United Express carrier for United's new hub at Washington–Dulles, but quickly floundered. In response, WestAir formed an eastern division to serve Dulles. WestAir itself experienced turmoil; in 1991 it spun off the new division into an independent company, Atlantic Coast Airlines (ACA), which years later would go on to become Independence Air.
In 1990, Mesa Airlines took over all of the United Express routes from Denver formerly operated by Aspen Airways except the Denver to Aspen route which went to Air Wisconsin. Mesa also added a number of new routes from Denver as well. In 1992 Mesa created a new division called California Pacific Airlines to begin new United Express service from the Los Angeles hub. In 1995, Mesa took over all United Express routes at the Seattle and Portland hubs formerly operated by WestAir. Mesa Airlines contract operating as United Express was cancelled in 1998 at which time Air Wisconsin and Great Lakes Airlines took over the Denver routes while SkyWest took over the Los Angeles, Seattle, and Portland routes.
In 1992, Great Lakes Airlines became a United Express partner, followed by Trans States Airlines the following year. In 1997, as United officially designated Los Angeles one of its hubs, SkyWest Airlines became a United Express partner as well. Great Lakes left the United Express system in early 2002, although it continued to do codeshare flights until they ceased operations in 2018.
From Wikipedia’s article on United Express, shared under CC BY-SA 4.0.2