During the 1910s, the United States Post Office had made a number of experimental trials of carrying mail by air. These were shown by the first stamp in the world to picture an airplane (captioned as "aeroplane carrying mail"), one of the U.S. Parcel Post stamps of 1912–13. The Post Office finally decided to inaugurate regular service on May 15, 1918, flying between Washington, D.C., Philadelphia, and New York City. The Post Office set a controversial rate of 24 cents for the service, much higher than the 3 cents for first-class mail of the time, and decided to issue a new stamp just for this rate, patriotically printed in red and blue, and depicting a Curtiss Jenny JN-4HM, the biplane especially modified for shuttling the mail. The stamp's designer, Clair Aubrey Houston, apparently troubled to procure a photograph of that modified model (produced by removing the second pilot seat from the JN-4HT to create space for mailbags, and by increasing the fuel capacity). As only six such aircraft existed, there was a 1-in-6 chance that the very plane engraved on the stamp by Marcus Baldwin—Jenny #38262—would be chosen to launch the inaugural three-city airmail run; the plane on the stamp was indeed the first to depart from Washington on May 15, taking off at 11:47 A. M.