Explained: this is why traffic lights are green, red and yellow

Colors

So how did these specific colors come about? Before traffic lights, trains were already using light signals to help manage the flow of train traffic. In these traffic signal lights, red meant stop, white meant go, and green meant “proceed with caution.” When white proved problematic (it could be mistaken for something else by train drivers, causing accidents), they changed the ‘go’ signal from white to green. Yellow was chosen as the color for “proceed with caution” as it was easier to recognize.

Red

But why red? Red is the color with the longest wavelength. This means you can see it from a greater distance. This is quite handy when it comes to warning signs and traffic lights that want you to stop to ensure safety. Now you know why the colors of traffic lights have a history of over a hundred years. This is definitely an interesting fact to share at a gathering!