When the Hoover Dam was completed in 1936,
it created a huge source of hydroelectric power
and zapped a sleepy desert town to life: Las Vegas, Nevada.
With the power supply from the dam,
Las Vegas soon exploded with vibrant displays.
The source of these dazzling lights was electrified neon gas.
There are two tricky obstacles to making lighted signs
out of this naturally clear, odorless gas:
capturing it and making it glow.
French inventor Georges Claude came up with techniques to do both.
In 1902,
he developed a way of liquefying and separating specific gases from the air,
producing neon on an industrial scale for the first time.
By 1910, he had come up with a way to trap the gas in a glass tube
with a special electrode at either end, and neon lighting was born.
In workshops like Claude's,
artisans known as tube-benders made neon signs by hand.
The tube-benders heated small sections of a long, hollow glass tube
and quickly bent them into shape.
After the glass cooled, they attached electrodes to each end
and removed the air with a vacuum pump.
Then, they passed a high voltage current through the tube
to remove any impurities on the inside of the glass.
Finally, they pumped the neon gas in and sealed off the electrodes.
When a neon sign is turned on,
the electric current causes some of the neon atoms' electrons to accelerate
and break free of their orbits, leaving behind positively charged ions.
As these free electrons rush from one electrode to the other,
they collide with more neon atoms, causing them to ionize as well.
When these excited electrons fall back to their normal energy levels,
their excess energy is carried away by photons, or particles of light.
All this happens in an instant,
and the glow from the photons is what we see when we switch on a neon sign.
Though it's common to call any gas-filled sign a "neon" sign,
there are actually 5 different gases used in production.
Each gas emits photons of a different wavelength when electrified,
which correspond to different colors of light.
Neon gives off an orange-red glow, argon glows a pale lavender,
helium a dusty pink, krypton a silver- white, and xenon a light purple.
These 5 gases can be combined with color-coated tubing
to create an electrified rainbow of text and images.
Business owners soon realized how effective these colorful beacons
were for attracting customers.
And unlike a light bulb, a neon sign has no incandescent filaments to burn out,
and can shine continuously for 40 years before the gas depletes.
By the 1930s, neon signs were lighting up storefronts all over the world.
Because of the glass tubes' fragile nature,
it usually wasn't feasible to ship them over long distances.
Instead, most neon signs were created by local neon shops
and then installed nearby.
Signs with humor, personality, and intricate designs proliferated,
no two exactly alike.
But by the end of World War II,
plastics had become widely available and inexpensive,
and plastic signs supplanted neon as messengers of modernity.
Many towns removed neon signs they viewed as old-fashioned.
Today, neon sign production is only a fraction of what it was at its peak,
but the craft of tube bending lives on relatively unchanged.
New creations hand-crafted by local artisans
join survivors from the heyday of neon,
hiding in plain sight in city streets around the world.