Air express service was set up to allow airlines a revenue source from business customers who generally shipped large parcels. Express labels would be applied showing the origin and destination of the goods as well as the charges or fees required for this service. The Railway Express Agency (R.E.A.) began operations on March 1, 1929 contracting with existing airlines to handle the items.
Harry A. Truby and James T. Schweier were experienced aerophilatelists who saw an opportunity to “send” mail via the air express service. They, along with a few others, would request that covers be sent generally on the first or last day of a particular air express route. The fee for most of these souvenir air express “covers” was $1.00 and would either be “PREPAID” at time of shipment or labeled as “COLLECT” when funds would be required at the destination point. Many covers were sent with postage affixed which was not required. The American Air Mail Catalogue covers the period between September, 1926 and September 1940 and lists only items known to the editors.
U.S. Post Office Department cancels were not required for express covers.
American Air Mail Catalogue Sixth Edition Volume One pp 106-120