Need for this stamp came from a decrease in air mail postage rates.
The Douglas DC-4 Skymaster was developed during World War II and led to the DC
-6 and DC-7 series with pressurized cabins.
The rapid development of aircraft was brought about by U.S. dominance of air
transportation during and after World War II. In 1951 the United States built
more than 80 percent of the world's airliners.