You’re sitting at a crossroad in a gridlocked city, staring at a glowing red bulb. It’s annoying. It’s also the only thing keeping you from a multi-car pileup. Most people think they know the answer to who invented the traffic light first, but the reality is way more cluttered than a simple name on a patent.
History isn't a straight line.
It’s a series of overlapping ideas, gas explosions, and guys in Cleveland getting fed up with horses crashing into early Ford Model Ts. If you ask a history buff in London, they’ll give you one name. Ask someone in Salt Lake City, and they’ll give you another. Honestly, the "first" depends entirely on how you define what a traffic light actually is. Is it a gas-powered lamp? An electric buzzer? Or the three-color system we actually use today?
The London Gas Experiment That Literally Blew Up
The quest to find out who invented the traffic light first usually starts in 1868. This was long before cars were a thing. London was a chaotic mess of horse-drawn carriages and pedestrians trying not to get trampled. A railway engineer named J.P. Knight had a "lightbulb" moment—though it wasn't an electric one.
Knight adapted the semaphore system used on railroads. He put up a 20-foot tall pillar outside the Houses of Parliament with arms that moved up and down. At night, it used red and green gas lamps.
Red meant stop. Green meant caution.
📖 Related: Who is Blue Origin and Why Should You Care About Bezos's Space Dream?
It worked. For a month. Then, a leak caused the gas to explode in a policeman’s face. The project was scrapped immediately. Londoners went back to dodging horse manure and carriage wheels for the next fifty years without any signals at all.
The American "Firsts" You’ve Probably Heard Of
Fast forward to the early 20th century in America. Cities were exploding in size. Suddenly, you had the "Gasoline Age" clashing with the "Horse and Buggy" era. It was a disaster.
In 1912, a Salt Lake City police officer named Lester Wire decided he’d had enough. He built a wooden box with red and green lights, dipped the bulbs in colored paint, and hooked it up to the overhead trolley wires. It looked like a birdhouse. People laughed at it. Because it wasn't patented, Wire often gets left out of the history books, which is kinda unfair if you think about it. He had a working electric signal years before the big names.
Then came James Hoge. In 1914, he installed a system in Cleveland at the corner of East 105th Street and Euclid Avenue. This is frequently cited as the first "official" electric traffic signal in the U.S. It had "STOP" and "MOVE" signs illuminated by electricity. It also had a loud buzzer that went off before the lights changed, presumably to give people a heart attack before they hit the gas.
Garrett Morgan and the Three-Position Leap
You can't talk about who invented the traffic light first without mentioning Garrett Morgan. Morgan was a brilliant Black inventor who saw a horrific accident between a car and a carriage in 1823. At the time, most signals were just Stop and Go. There was no "Yellow" or "Wait" phase.
👉 See also: The Dogger Bank Wind Farm Is Huge—Here Is What You Actually Need To Know
Morgan’s genius wasn’t just the light; it was the interval. He patented a T-shaped signal that had a third "all-stop" position. This stopped traffic in all directions so pedestrians could cross safely. He eventually sold the rights to General Electric for $40,000, which was a massive fortune back then. While he didn't "invent" the light itself, he invented the safety flow that makes modern driving possible.
Why William Potts is the Hero No One Remembers
If you’re looking for the person who actually gave us the red, yellow, and green lights we see today, you’re looking for William Potts.
Potts was a Detroit police officer. In 1920, he realized that the two-color systems weren't cutting it for the heavy traffic of the Motor City. He took railroad signal technology and adapted it for street use. He was the first to use the three-color system on four-way signals.
The crazy part? Because he was a government employee (a cop), he couldn’t patent it. He never made a dime from the invention that basically governs every city on Earth. He just wanted the streets to be less of a death trap.
The Evolution of the Tech: From Bulbs to AI
We've come a long way from gas lamps exploding in the faces of Victorian bobbies. Modern traffic management is moving away from simple timers and toward what engineers call "Adaptive Signal Control Technology" (ASCT).
✨ Don't miss: How to Convert Kilograms to Milligrams Without Making a Mess of the Math
- Inductive Loop Sensors: Those wires buried in the asphalt that sense your car’s metal frame.
- Microwave Radar: Used to detect pedestrians and adjust "Walk" times.
- Computer Vision: Cameras that use AI to count cars and prevent a light from staying green for an empty street.
It’s interesting to note that even with all this tech, we are still using the basic colors established by Potts and the interval logic pioneered by Morgan. The "first" wasn't a single event—it was a relay race.
What Most People Get Wrong About Traffic History
There’s a common myth that the traffic light was invented to help cars. It wasn't. It was invented to protect pedestrians and horses from the new, terrifying "horseless carriages" that were zig-zagging through cities without any rules.
Another misconception is that the colors were random. Red has been the universal sign for danger or "stop" in maritime and rail for centuries because it has the longest wavelength in the visible spectrum. It’s the easiest color to see through fog or rain. Green was originally "caution" in some rail systems, and white was "clear," but after a few train crashes (caused by the red lens falling off a lamp and showing a white "clear" light), they switched green to mean go.
Actionable Takeaways for the Curious Mind
Knowing who invented the traffic light first isn't just trivia; it’s a lesson in how innovation actually happens through iteration. If you’re interested in the intersection of history and urban planning, here is how you can dig deeper:
- Check Local Archives: Many cities (like Cleveland or Detroit) have original patent drawings or photos of their "first" lights in their public libraries.
- Observe the Sensors: Next time you’re at a light, look for the rectangular cuts in the pavement. Those are the inductive loops. Knowing they are there helps you position your car correctly to "trip" the light.
- Read Up on Garrett Morgan: His life story is incredible beyond just the traffic light—he also invented an early version of the gas mask used in WWI.
- Explore Smart Cities: Look into how your specific city is currently upgrading its grid. Most major metros are currently replacing old incandescent bulbs with LEDs to save millions in energy costs.
The next time you're stuck at a red light, remember Lester Wire’s painted birdhouse or William Potts’ unpatented genius. Traffic lights are a masterpiece of collaborative, messy, human engineering that keeps the world moving, one color at a time.
Sources for Further Reading:
- The Smithsonian Institution’s records on Garrett Morgan.
- The Cleveland Historical Society’s archives on the 1914 electric signal.
- Traffic Engineering manuals from the Institute of Transportation Engineers (ITE).