The award and inauguration of Pennsylvania-Central Airlines' Air Mail Route 41 constituted, in effect, the re-institution and extension of the Michigan Upper Peninsula's previous Contract Air Mail Route 27 service, discontinued by the contract cancellations of 1934.

This cover was carried on the July 20, 1938 inaugural Air Mail Route 41 flight from Flint, Michigan to Detroit, Michigan and is listed in the Contract Air Mail Flights (CAM) Section of The American Air Mail Catalogue as 41S2.

Pennsylvania-Central Airlines changed its name to Capital Airlines on April 28, 1948.

On June 1, 1961, Capital Airlines was formally merged into United Air Lines.