After the war, surplus Jennys were widely used for "barnstorming"—traveling air shows—and they opened the first scheduled air mail service.
Early airlines were able to turn a profit through contracts with the federal government to fly the mail. Designed as a trainer for the U.S. Army Air Service, the Curtiss JN-4 first flew in 1916. Known popularly as the "Jenny," the JN-4 taught thousands of Allied pilots to fly during World War I. After the war, surplus Jennys were widely used for "barnstorming"—traveling air shows—and they opened the first scheduled air mail service.