These 6c airmail stamps show a twin-motored transport plane. Both the sheet and the booklet versions are shown. They are part of the transport plane set.
This stamp commemorates the 50th anniversary of Lindbergh‘s solo flight across the Atlantic.
This stamp commemorates the 50th anniversary of the first contract airmail flights. Those first flights went from Dearborn, Michigan, to Cleveland, Ohio, and from Pasco, Washington, to Elko, Nevada.