The neon sign is an evolution of the earlier Geissler tube,
which is an electrified glass tube containing a “rarefied” gas
(the gas pressure in the tube is well below atmospheric
pressure). When a voltage is applied to electrodes inserted
through the glass, an electrical glow discharge results. In
1923, Georges Claude and his French company Claude Neon
introduced neon gas signs to the United States by selling two to
a Packard car dealership in Los Angeles. Neon lighting quickly
became a popular fixture in outdoor advertising. Visible even in
daylight, people would stop and stare at the first neon signs
for hours, dubbed "liquid fire.