First U.S. air mail was flown by army pilots in army airplanes.

They used the Curtiss JN-4D, which was nicknamed the "Jenny" because of the
first two letters of the designation.

The Jenny was a series of single-engine biplane trainers that became this
country's best-known World War I two-seat trainer.

It went through a number of iterations, with the JN-4D version having a
wingspan of 44 feet (13.4 m). It was powered by a 90-horsepower Curtiss OX-5
engine.

After World War I, Jennys were shifted to civilian aviation and were used in
barnstorming, air shows, and for private transportation.