You’re sitting at a red light, tapping your fingers on the steering wheel, probably wondering why it’s taking so long to turn green. It’s one of those universal human experiences. We all hate waiting, but we’d be in total chaos without those three glowing circles. Most people think there’s one simple answer to who created the traffic light, but history is never that clean. It wasn't just one guy having a "Eureka!" moment in a lab. It was a messy, decades-long process involving gas explosions, high-school dropouts, and a whole lot of horse manure.
The streets of the 1800s were a nightmare. Imagine London in 1868. It wasn't cars you had to worry about; it was thousands of horses, heavy carriages, and pedestrians all fighting for the same inch of cobblestone. It was loud. It was smelly. And it was incredibly dangerous.
The explosive start in London
John Peake Knight is usually the first name that pops up when you dig into the archives. He was a railway signaling engineer. In 1868, he figured if his semaphore system worked for trains, it could work for the bridge near the Houses of Parliament. This thing didn't look like what we have today. It had wooden arms that moved up and down, and at night, it used red and green gas lamps.
It worked. Sort of.
The problem was that gas is volatile. About a month after it was installed, a leak caused the whole thing to blow up in a policeman's face. The project was scrapped immediately. Londoners went back to dodging horse hooves for the next fifty years. It’s kind of wild to think that the very first attempt at a traffic signal ended in a literal fireball, but that’s early engineering for you.
Garrett Morgan and the middle yellow light
Fast forward to the early 1920s in America. Cars are everywhere now. The Ford Model T made driving affordable, but the roads weren't ready. This is where Garrett Morgan enters the story. Morgan was a brilliant Black inventor from Cleveland who had already made a name for himself with a "smoke hood" (an early gas mask).
The story goes that Morgan witnessed a horrific carriage accident at an intersection. At the time, most signals were just "Stop" and "Go." There was no warning. One second you're moving, the next you're supposed to be still. Morgan realized there needed to be a "wait" or "caution" interval to let the intersection clear.
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In 1923, he patented a T-shaped signal with three positions. While he didn't "invent" the three-color light we see today (that was more of an evolution), his contribution was massive because he focused on the flow of traffic rather than just stopping it. He eventually sold the rights to General Electric for $40,000. That was a fortune back then. It changed everything.
The Detroit connection and the electric era
While Morgan was working in Cleveland, a policeman in Detroit named William Potts was getting creative. Detroit was the "Motor City," and the traffic was arguably the worst in the world at the time. Potts was tired of manually operating four different signals at one intersection.
In 1920, Potts took bits and pieces from railroad signals and wired them together. He was the first to use the actual red, amber, and green electric lights in a four-way configuration. Here’s the kicker: because he was a city employee, he never actually patented it. He just wanted to fix the traffic on his beat.
If you're looking for the person who created the traffic light in its most modern, electric form, Potts has a very strong claim. But because he didn't file the paperwork, his name often gets lost in the shuffle of patent history.
Why it matters more than you think
It's easy to dismiss this as just some trivia about poles and bulbs. But the traffic light changed the architecture of our world. Before signals, cities were built for walking. Once we could control the flow of cars, we started building suburbs. We started building "commutes."
We take the colors for granted, too. Why red? Why green? It actually comes from the maritime and railroad traditions. Red has the longest wavelength in the visible spectrum, meaning it scatters the least and can be seen from the furthest distance—crucial when you're trying to stop a heavy train or a car on a rainy night. Green was actually "caution" in early railroading, and white was "clear." That caused a lot of deaths because a red lens would sometimes fall out, leaving a white light that engineers thought meant "go." Eventually, green became the universal "go."
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Lester Wire and the Salt Lake City experiment
We can't talk about this without mentioning Lester Wire. He was another policeman, this time in Salt Lake City, around 1912. He built a wooden birdhouse-looking box with red and green lights dipped in paint. It was hooked up to the overhead trolley wires.
People laughed at it. They called it "Wire's Birdcage."
But Lester was onto something. He realized that traffic shouldn't be controlled by a man waving his arms in the middle of the street. It was too dangerous for the cops. His invention was purely functional, born out of a desire to not get run over by a reckless driver in a Maxwell Runabout.
The myth of the "One Inventor"
Honestly, the search for a single person who created the traffic light is a bit of a wild goose chase. Technology doesn't happen in a vacuum. It’s a series of iterations.
- John Peake Knight brought the idea from the tracks to the streets.
- Lester Wire made it electric.
- William Potts made it four-way and three-colored.
- Garrett Morgan added the crucial "caution" timing and patented a version that could be mass-produced.
Each of these men looked at a chaotic intersection and saw a problem that needed solving. They weren't just making lights; they were inventing a way for millions of people to live in close quarters without killing each other every time they went to the grocery store.
The future: Will the lights go out?
Today, we're moving into the era of "Smart Infrastructure." Engineers are currently working on systems where cars "talk" to the traffic lights. In some experimental setups, the light doesn't even need to be there. Your dashboard tells you when to go, or the self-driving car just coordinates with the other cars via 5G.
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We’re basically coming full circle. We went from human hands waving flags, to gas-powered arms, to electric bulbs, and now to invisible data packets.
If you want to dive deeper into how our cities evolved, start by looking at your local historical society’s archives for old street photos. You’ll see the transition from chaos to order in real-time. Also, if you’re ever in Cleveland, the Western Reserve Historical Society has Garrett Morgan's original signal. It’s a huge, towering piece of history that looks more like a piece of industrial art than a piece of road equipment.
How to apply this history today
Next time you're stuck at a long light, don't just fume. Use that time to observe the intersection. Notice how the sensors (those loops cut into the asphalt) detect your car. Understanding that this system was built by a handful of cops and engineers trying to save lives makes the wait a little more bearable.
- Check for "Inductive Loops": Look for the rectangular cutouts in the pavement near the stop line. That's the modern version of William Potts' brain.
- Support local museums: Many of the original signals from the 1920s are rotting in basements. Seeing them in person gives you a real sense of the scale these inventors were working with.
- Research Garrett Morgan: His life beyond the traffic light is fascinating—he was a hero in a real-life tunnel rescue and a prominent voice for civil rights.
The street isn't just a way to get from A to B. It’s a living museum of engineering. The fact that you can drive across an entire country and every single red light means the same thing is a miracle of human cooperation. We didn't just invent a light; we invented a global language.
Actionable Insight: If you’re interested in urban planning or the history of technology, look into the "Green Wave" synchronization used in many major cities. It’s a modern application of the timing principles Garrett Morgan first envisioned, designed to keep traffic moving at a steady pace to reduce emissions and frustration. Observe the timing on your next drive and see if you can spot the pattern.