The idea that red means stop and green means go has impacted our lives in more ways than just traffic signals. We have been taught from a young age that the color red means danger and the color green means it’s OK to move forward. But why were those particular colors chosen for traffic lights in the first place? For something we have to look at every day, why couldn’t they have been prettier colors like magenta and turquoise?
Well, it’s important to know that before there were traffic lights for cars, there were traffic signals for trains. At first, railroad companies used red to mean stop, white to mean go, and green to mean caution. As you could imagine, train conductors ran into a few problems with the color white meaning go—bright white could easily be mistaken for stars at night, with train conductors thinking they were all clear when they really weren’t. Railway companies eventually moved to the color green meaning go, and it’s been that way ever since—except in Japan, where you’ll find an entirely different color that signals “go.”
As far as red goes, that’s always been a color that indicated danger, long before cars were even around. Red is the color with the longest wavelength, so it can be seen from a greater distance than other colors. The color yellow was used to caution drivers because it has a slightly shorter wavelength than red, but not as short as green.
But, believe it or not, yellow was once used to mean stop, at least as far as signage goes. Back in the 1900s, some stop signs were yellow because it was too hard to see a red sign in a poorly lit area. Eventually, materials were developed that were highly reflective and red stop signs were born. Since yellow can be seen well at all times of the day, school zones, some traffic signs, and school buses continue to be painted yellow. Keep these safe driving tips in the back of your mind whenever you see a yellow light.
So next time you’re impatiently waiting at a traffic light, don’t get so mad; employ these driving etiquette rules first and know that traffic lights have certainly come a long way.