Air Mail Route 74 was inaugurated in an easterly direction on May 10, 1947. Although unfavorable weather delayed the western flight for three days, some westbound covers received May 10 postmarks.

This cover was carried on the inaugural Air Mail Route 74 flight from the Salt Lake City, Utah Airport Mail Facility to Denver, Colorado (where it was backstamped) and is listed in the Contract Mail Mail Flights (CAM) Section of The American Air Mail Catalogue as 74E7f.

On June 1, 1950 Monarch Air Lines, Challenger Airlines, and Phoenix-based Arizona Airways merged to form Frontier Airlines.  The newly-formed airline had 400 employees and 12 Douglas DC-3 aircraft, serving 40 destinations in the Rocky Mountain region.

 Frontier Airlines’ shareholders and the Department of Transportation approved the airlines’ merger with People Express on Tuesday, November 21, 1985, officially ending Frontier Airlines’ 39-year era as one of the west’s major independent air carriers. People Express, based in Newark, N.J., bought the Denver-based Frontier Airlines on October 9, outbidding Texas Air Corporation and a coalition of Frontier unions. With the Department of Transportation’s actions, Frontier Airlines officially became a wholly owned subsidiary of People Express, Inc.

On August 24, 1986 Frontier Airlines ceased operations and released all of its employees as the result of financial difficulties. On August 28, 1986, the airline filed for bankruptcy under Chapter 11 of the Federal Bankruptcy Code.

On October 17, 1986, the bankruptcy court approved the purchase by Continental Airlines’ parent corporation, Texas Air, of the assets of Frontier Airlines. The Frontier acquisition was one of several conditions established by Texas Air as requirements for its acquisition of People Express, Inc., Frontier’s parent company. The equipment and routes of Frontier were sold to Continental Airlines which reinstated many of the old Frontier routes using the purchased Frontier equipment and by rehiring many of the old Frontier employees.