Northeast Airlines added Philadelphia to Air Mail Route 27 with service to Washington, DC and Boston, Massachusetts on June 27, 1957. 

Northeast Airlines provided unofficial cachets and most of the offices involved dispatched collector covers on the inaugural flights.  

This cover was carried on the inaugural Air Mail Route 27 flight from the Philadelphia, Pennsylvania Airport Mail Facility to Oak Bluffs, Massachusetts (where it was backstamped) and is listed in the Contract Air Mail Flights (CAM) Section of The American Air Mail Catalogue as AM27N103f.

Northeast Airlines was acquired by Delta Air Lines.  The effective date of the merger was August 1, 1972.