Who Invented The Traffic Light? 3 Incredible Humans

who invented the traffic light

Traffic Light Inventions

Are you wondering who invented the traffic light? Look no further. In this article we will drive right into all of the juicy details. And we will find out how this all began. Not sure about you, but personally I love traffic lights. I wish I was the one who invented it. But, sadly it wasn’t me.

For the short answer, Garrett Morgan, J.P. Knight, and William Potts were the traffic light inventors.The inventing didn’t happen overnight. It was a process, of course.

People sometimes call traffic lights, traffic signals. Us humans have installed traffic signals are all over the world at intersections, and sometimes not at an intersection.

They let all of the different road users know when they should take the right of way and go. And when they should let other road users proceed on their way.

who invented the traffic light

Who Invented The Traffic Light – Before Automobiles

Before automobiles there were still traffic jams full of horse-drawn carriages and pedestrians

Horse drawn carriage

What was the first city in the world to have a traffic light?

People experienced traffic jams much before the invention of cars. Horse-drawn carriages, as well as pedestrians, caused huge crowds in London in the 1860’s.

A British railway manager called John Peake Knight, started thinking about traffic control. He suggested adapting a railroad method for this problem.

The railroads at the time used a semaphore system. This included small arms extending from a pole to let trains know whether they could pass or not.

For Knight’s idea to adapt this system, the semaphores would signal ‘stop’ and ‘go’ during the day. At night, it featured red and green lights. Lamps – powered by gasoline – would light up the sign at night.

A police officer operated the lights.

Who Invented The Traffic Light – World’s First Traffic Light

Westminster (London) had the very first traffic light known to history installed on December 9, 1868.

Humans installed it at the intersection of Bridge Street and Great George Street in Westminster (London). People who used the light and observed the intersection operation considered it a success, and more traffic lights were anticipated.

That intersection seems to look a little different nowadays.

Westminster London Intersection

Sadly only a month later, the traffic light injured a police officer pretty badly. A leak in a gas main caused one of the lights to explode right in his face – ouch.

Officials declared a public health hazard, and immediately stopped the project.

Traffic Light Patents

Approximately 40 years past after that incident before the traffic light gained some more popularity. In the early 1900’s, several people filed patents as more and more automobiles were hitting the road, mostly in the states.

In 1910 Ernest Sirrine who was an American inventor, showed the world an automatic traffic signal. That was in Chicago. His traffic signal had two display arms. These were not illuminated.

The display arms were arranged as a cross. It rotated on an axis, and said ‘stop’ and ‘proceed.’

Lester Farnsworth Wire invented the very first electric-controlled traffic light in 1912.

It used red and green lights, but a police office had to manually switch the direction of the lights. The traffic light was like a four-sided bird house which was mounted onto a tall pole, in the middle of the intersection. This was in Salt Lake City, Utah.

Who Invented The Traffic Light – First Ever Electric Traffic Signal

Official credit for the very first electric traffic signal is usually found with James Hoge. A traffic signal design was installed on August 5, 1914 in Cleveland using his design. He received a patent for his marvelous invention in 1918, after filing in 1913.

This traffic signal used alternating ‘stop’ and ‘move’ illuminated words, installed on a signal post, one on each corner of the intersection. Police and fire could make adjustments to the rhythm in case of an emergency situation.

William Ghiglieri, from San Francisco patented the first traffic signal that was using red and green lights. This was in 1917. His design had options; it could be either automatic or manual.

Who Invented The Traffic Light: Yellow Light Credit

Who invented the traffic light in 1920?

In 1920, William Potts developed the yellow caution light. He was a Detroit police officer. He worked on the first 3-color signal, including the beautiful yellow (or amber) light.

Who invented the 3 color traffic light?

In 1923, Garrett MorganOpens in a new tab. patented another electric, automatic traffic light. He was the first African-American to own a car in Cleveland. This design used a T-shaped pole. It had 3 positions.

This man also invented a gas mask while he was at it!

One of the unique features about this design is that people could replicate the design in a cost-effective way. Therefore, additional units were made and installed. Morgan later sold the rights to his traffic signal invention to General Electric. That was for $40,000. I think I would have done so as well!

Read more: Traffic light visibility and buses or large vehicles

Who Invented The Traffic Light – Are traffic lights the same in all countries?

Basically the answer to this is yes. All around the world, it seems a universal language that traffic light colors are green, yellow and red. This is great news for world travelers, of course.

What are traffic lights called in America?

In Britain the light is typically attached to a vertical pole and people there call it simply a traffic light. In the US, it’s usually adjoined to a horizontal overhanging beam.

It is known as a traffic light or stop light or just light.


I’m actually glad it wasn’t me who invented the traffic light because that would make me very old right now. It seemed like a dangerous process, but I guess that is true for many inventions. Someone’s gotta do it. Today I don’t mind driving through traffic lights.

Just have to watch out for when they aren’t working and are supposed to turn into a 4-way stop. That’s a nice idea, it’s just that 4-way stops aren’t usually 5 lanes in each direction. But, traffic lights mostly work great to control traffic. And I’m glad that some folks invented them for us.


Carmen became a driving instructor at the age of 22 in North Vancouver, Canada and is an experienced writer, blogger, photographer, artist, philosopher, certified day dreamer and generally complicated human.

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