The inverted Jenny (or Jenny invert, the famous 'JN4' (aka 'Jenny) WWI 2-seater airplane made by Curtiss company ) is a United States postage stamp of 1918 in which the airplane in the center of the design was accidentally printed upside-down . Only 100 of the inverts were ever found , making this error one of the most prized in all philately; as of 2003, an inverted Jenny would typically sell for around US$150,000 . During the 1910s, the United States Post Office had made a number of experimental trials of carrying mail by air, and 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, the biplane chosen to carry the mail.