12. Development of Air Mail Service
Established on May 15, 1918, the U.S. Air Mail Service began regular flights between Washington, D.C., Philadelphia, and New York City, using converted military aircraft. This initiative demonstrated the viability of air transport for commerce, leading to the expansion of airmail routes across the nation. The experimentation during this period refined navigation, reliability, and aircraft design, laying the groundwork for today’s worldwide postal and cargo air networks. (postalmuseum.si.edu)
