Prior to the inaugural of Air Mail Route 57, connecting service between Seattle and Vancouver had been furnished by the Canadian government. The initial flight under that service occurred on October 2, 1935.

As of May 12, 1941 air mail service was performed under United States contract and was designated as Air Mail Route 57.

The Canadian did not provide an official cachet for the inaugural mail at Vancouver.

This cover was carried on the inaugural United Airlines from Vancouver, Canada to Seattle, Washington (where it was backstamped by the airline) and is listed in the Contract Air Mail Flights (CAM) section of The American Air Mail Catalogue as 57S2.

Albert Brown, a noted air mail historian, prepared the cover.