On this day in 1920, the way people drove was changed forever when a Detroit traffic cop installed a four-way, tri-color traffic signal on Woodward Avenue in Detroit, according to the Detroit Historical Society.
His name was William Potts, and his new traffic signal would go on to become the norm for roadways all over the country, and it was all because he added the yellow light.
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Before Potts invented a traffic signal with three colors, all drivers had was red and green. Red was meant for stop, and of course, green meant go. As you can imagine, have just go and stop as traffic signals cause a lot of headaches and accidents for drivers. Coming to an immediate stop is bad enough, but imagine it in a car from the 1920s.
Potts changed the game when he invented the new traffic signal by adding the yellow light, which gave drivers some time to come to a complete stop before the light turned red. It was a simple solution, but one that changed America forever.
The traffic signal also had four sides, so it was perfect for busy intersections that were popping up more and more across the country.
The light was installed at the corner of Woodward Avenue and Fort Street in Detroit, and the rest is history. The new traffic signal was everywhere by the mid-1930s.
Luckily for Detroiters, they can see the original traffic signal at The Henry Ford Museum in Dearborn, Michigan. The light was donated to the museum by the Detroit Police Department some years ago, and you can see it when you’re walking through the Driving America section of the museum.
We use traffic signals every day of our lives, and it’s pretty poetic that it was invented in the city that brought cars to America in the first place.