On November 20, 1923, the U.S. Patent Office granted a patent to Garrett Morgan for his three-position traffic signal. Here are 5 facts you probably didn't know about the traffic light...
Traffic Lights Were Invented by a Former Detective Lester Wire was a Salt Lake City detective who conceived the idea of electronically controlled traffic lights in 1912. At the time, patrolmen were required to direct the traffic at a busy intersection, so he used a wooden box with green and red lights on all sides, mounted it on a pole and wired it to the electric lines used for trolley cars. A patrolman was still needed because it was operated manually, but the officer could sit comfortably in a booth and out of the weather to direct traffic.
Cleveland Boasted the First Traffic Light in the Country The first four-way signal was placed at the busy intersection of East 105th and Euclid Avenue in Cleveland, Ohio, on August 5, 1914. It was controlled by a police officer from a booth, the same as those invented by Lester Wire. Although the first electric traffic signal had red and green lights only, it was the first use of a modern signal.
The Yellow Light Didn't Exist Until The 1920s It was obvious fairly early on that having only green and red lights on a traffic signal might be a problem because drivers had no warning when to slow down except for a buzzer or warning whistle, and the traffic signals caused a lot of collisions. By 1920, William Potts, a police officer in Detroit, had added a yellow signal light to warn motorists that the light was about to change. Although Officer Potts used it, the patent for this invention was credited to Garrett Morgan in 1923. Morgan ended up selling his patent to General Electric.
One of the Oldest Traffic Lights Is Still in Use Ashville, Ohio, is home to the oldest traffic light that is still operational. It looks less like a traffic light and more like a spaceship with its oval shape, metal finish and one light in the middle like a giant eye, but it was installed in 1932. Amazingly, it has been in operation for more than 80 years.
Railroad Lights Were the Inspiration for the Colors Used The traffic light was modeled after the signals used on railroad tracks and crossings. There's little evidence as to why the colors red and green were chosen to represent "stop" and "go." But science has validated the decision: because red light has a longer wavelength than green, it can be seen from farther away. The sooner you see the light, the sooner you hit the brakes.