During World War I, the United States manufactured a significant number of Curtiss JN-4 “Jenny” biplanes to train its military aviators, and almost every U.S. airman learned to fly using the plane. After the war the U.S. federal government sold off the surplus material, including the Jennys, for a fraction of its initial value (they had cost the government $5,000 but were being sold for as low as $200).[1] This allowed many servicemen who already knew how to fly the JN-4s to purchase their own planes. The similar-looking Standard J-1 biplane was also available.