Clifford Ball Airlines First Flight Pittsburgh PA 1927
Serving the steel centers of the Midwest, Contract Air Mail Route 11 was inaugurated on April 21, 1927 with service provided by three Waco 9 biplanes. The Cleveland, Ohio terminal was the Glenn Martin Airplane Factory Field. Pittsburgh and McKeesport, Pennsylvania both dispatched mail through Bettis Field in McKeesport. Shortly thereafter, Youngstown was dropped from the schedule as Lansdowne Field was found unsatisfactory.
The cover was carried on the inaugural northbound Contract Air Mail Route 11 flight from Pittsburgh and is listed in Contract Air Mail Flights (CAM) Section of The American Air Mail Catalogue as 11N4.