The first US Airmail coil stamp was issued on January 15, 1948, in Washington, DC. Only a few more coil stamps would be issued over the next 30 years, but the DC-4 SkyMaster would appear on more than a dozen postal items.
The DC-4 SkyMaster made its maiden flight on February 14, 1942. The aircraft quickly played a critical role in the Allied war effort and the Berlin Airlift of 1948-49. The SkyMaster was also widely used in commercial aviation and to deliver airmail.