It also operated feeder flights on behalf of Braniff (1983–1990) and Ozark Air Lines in addition to flying for Mesa Airlines.

In 1977, Frontier withdrew all service at Garden City, Goodland, and Hays, KS as well as Lamar, CO and Air Midwest began operating a fleet of six Swearingen Metroliner commuter propjets.

This new service to New Mexico was connected to the Kansas operations by serving Lubbock, Texas where Air Midwest partnered with Braniff Airways.

Beginning in 1984, competitor Mesa Airlines began aggressive expansion throughout New Mexico and Texas and Air Midwest made the decision to discontinue all routes in this area on January 31, 1986.

Meanwhile, Air Midwest subsequently discovered many hidden problems with the neglected fleet inherited from Scheduled Skyways, forcing the airline to perform a great deal of maintenance to keep the aircraft flying.

On April 1, 1985, Air Midwest introduced the 30-seat Saab 340 turboprop aircraft with flights from Kansas City to Wichita, Omaha, and Manhattan, KS.

Although Air Midwest was unsuccessful in gaining a codeshare with Republic through the Scheduled Skyways merger, it was able to acquire codeshare agreements in 1985 with Eastern Airlines as Eastern Air Midwest Express at the Kansas City and Wichita hubs and in 1986 with Ozark Air Lines as Ozark Midwest at that carriers' St. Louis hub, as well as with American Airlines as part of the American Eagle (airline brand) at their newly created Nashville hub.

Continuing money problems forced Air Midwest to sell its Nashville hub and Saab 340 aircraft to American in 1987.

Eastern then abruptly downsized its Kansas City hub operation thus leaving Air Midwest with no one to connect passenger traffic to.

In 2001 all Mesa Airlines flights operating with Beech 1900D's at the Albuquerque and Phoenix hubs were transferred to the Air Midwest certificate.

[9] A book on the history of Air Midwest entitled "Pioneer of the Third Level" was written by Dr. Imre E. Quastler, an authority on regional airlines.

[10] From 1991 until 1997, Air Midwest operated twelve Beechcraft 1900C commuter turboprops flying from its Kansas City hub as USAir Express.

For a period of three weeks in August 2006, Air Midwest operated as Delta Connection, flying three Beechcraft 1900D from John F. Kennedy Airport to Providence, Rhode Island, and Windsor Locks, Connecticut, as a stop-gap measure for Freedom Airlines, another subsidiary of Mesa Air Group, until it was relieved by Chautauqua Airlines.

A report published in The Wall Street Journal on January 14, 2008, included a statement from Mesa CEO Jonathan G. Ornstein that the company had decided to shut down Air Midwest, citing significant losses stemming from increased maintenance and fuel costs.

All cities served by Air Midwest received notices of intention to end service, except for Prescott and Kingman, Arizona.