On May 15, 1918, the United States officially established regularly scheduled airmail service with flights between Washington, D.C., Philadelphia, and New York City. Army planes and civilian pilots were used on the first flights. Airmail stamps were used to distinguish between regular mail.

Two days before the initial flight, the world's first stamp, printed by the Bureau of Engraving and Printing designed expressly for airmail was issued to pay the rate between any two of the three cities.

24¢ for the first ounce, including special delivery. Later in the year, the airmail rate dropped to 16¢, at which time another stamp was issued. Near the end of the year, the Curttis Jenny stamp was issued, a 6¢ stamp which paid the airmail rate without special delivery.