Due to a restriction in the Civil Aeronautics Board award, no covers were dispatched from Des Moines northeast to Milwaukee or from Milwaukee to Des Moines. Collector covers intended for dispatch on these segments received an official cachet and an additional marking indicating that “No CAB Authority Granted For Services Between Milwaukee & Des Moines.”  In addition, collector covers submitted to the Milwaukee Airport Mail Facility also received the official cachet with an additional marking “No AMF Service Available At Milwaukee, Wisconsin.”

The Civil Aeronautics Board and President Lyndon Johnson approved the simultaneous merger of three airlines for the first time in early 1968. Pacific Air Lines, Bonanza Airlines, and West Coast Airlines were combined to form Air West. Air West provided service to eight Western states, Canada, and Mexico within its 8,800-mile system.

Hughes Airwest was a regional airline in the western United States, backed by Howard Hughes' Summa Corporation. Its original name in 1968 was Air West and the air carrier was owned by Nick Bez. Hughes Airwest flew routes in the western U.S. and to several destinations in Mexico and Canada; its headquarters were on the grounds of San Francisco International Airport (SFO) in unincorporated San Mateo County, California.

With distinctive all-yellow aircraft, the company slogan was Top Banana in the West. Hughes Airwest was purchased by Republic Airlines on October 1, 1980.