Who really invented the yellow traffic light? – Jalopnik

Ah, the yellow light. You know, that signal that’s supposed to tell you to slow down as you approach the intersection, but instead makes you speed up? You probably take it for granted, but traffic lights were not always equipped with a yellow light. Traffic lights have existed since before the advent of motor cars, from the mid-19th century and regulated horse-drawn carriage traffic in London. The first gas version did not last long as it exploded killing the officer operating it. In 1914, electrical signals entered the scene. But they only had two lights: green for ‘go’ and red for ‘stop’, with no warning that the light was about to change. You can imagine how that turned out. Eventually, people had enough of collisions at busy intersections and several inventors started working on solutions.

Here came Garrett Morgan. Morgan was already a successful inventor, having invented a safety hood that would be used by fire departments and accidentally invented a chemical hair relaxer that became popular with black men. In the 1920s, Morgan decided to do something about all these traffic accidents at intersections and invented a traffic light that required all traffic to stop to clear an intersection before it could stop or leave. He received a patent for it in 1923. Hooray, the warning signal was invented!

Not so fast. A police officer by the name of William Potts brought the three-light traffic light to the streets of Detroit in 1920. Its traffic lights looked much the same as traffic lights today, with red, yellow and green lights. Although Morgan’s traffic light would influence the way traffic would be managed for years to come, Potts was actually the inventor of the yellow traffic light as we know it today.

Potts took his inspiration from railway signals, which already used yellow or amber lights. Railroad signals today were similar to traffic lights on the street. They had three lights: red for stop, green for go and yellow for ‘proceed carefully’. Potts built something similar and placed his lamps in a four-sided box.

The new three-light signal was installed in 1920 at Detroit’s busy Fort Street and Woodward Avenue intersection, where more than 20,000 vehicles passed daily. We didn’t even know there were 20,000 vehicles in Detroit in 1920. The city of Detroit would completely adopt Potts’ invention and use it throughout the city. By the 1930s it was used nationwide, and in 1935 the Manual on Uniform Traffic Control Devices declared Potts’ design the standard for traffic signals. And they haven’t really changed all that much a century later (although Japan uses blue lights instead of green for some reason), but we’d like to know what Mr. Potts would have thought about traffic cameras.

One of his inventions came about when he tried to create a chemical solution to prevent sewing machine needles from burning. Instead, he accidentally discovered that the solution could cause the hair to lay flat. And so he launched GA Morgan’s Hair Refiner, which became quite popular among black men. He would later invent the safety hood, a precursor to modern gas masks. In 1916, workers became trapped in a tunnel being dug under Lake Erie when they came across a pocket of natural gas. Morgan and his brother put on safety hoods and rescued two of the workers. The US Army made a deal with Morgan to supply them with safety covers for use in World War I.

In the 1920s, he created a semaphore-type traffic light that was manually turned on and would throw up “stop and go” signs, as well as one for “all-stop,” meaning traffic in all directions would stop to clear the intersection. Unfortunately, this signal would not become the standard. But don’t feel sorry for Morgan. General Electric would buy the rights to his patent in 1923 for $40,000, which was a pile of bills at the time. Garrett Morgan didn’t invent the yellow light, but he did just fine for himself.