The 13-cent Commercial Aviation stamp (Scott 1684) was issued by the United States Postal Service on May 19, 1976, in observance of the 50th anniversary of the first contract airmail (CAM) flights. The design by Robert E. Cunningham depicts two early airplanes, a Ford-Pullman Monoplane and a Laird Swallow Biplane.
The blue and multicolored stamp was printed on the Bureau of Engraving and Printing seven-color Andreotti gravure press (601) as sheets of two hundred subjects, tagged, perforated 11, and distributed as panes of fifty. Mr. Zip, “MAIL EARLY IN THE DAY,” and five plate numbers, one in each color used to print the sheet, are printed in the selvage.
The first CAMs began operating in February 1926 after the U.S. Post Office Department signed contracts with private air companies to carry the mail. The CAM routes were established primarily as feeder routes to the transcontinental route. On February 15, 1926, a Ford-Pullman Monoplane flew the first CAM route from Dearborn, Michigan, to Cleveland, Ohio. On April 6, 1926, pilot Leon D. Cuddeback flew the Pasco, Washington, to Elko, Nevada, CAM route, awarded to Walter T. Varney (Varney Air Lines, known today as United Air Lines), in a Laird Swallow Biplane.
Scott 2005 Specialized Catalogue of U.S. Stamps and Covers
Encyclopedia of United States Stamps and Stamp Collecting
National Postal Museum, Smithsonian (http://www.postalmuseum.si.edu/airmail/objectshowcase/stampcovers/object_stampscovers_cams.html)
U.S. Centennial of Flight Commission (http://www.centennialofflight.gov/essay/Commercial_Aviation/1920s/Tran1.htm)