Red for “stop” makes sense. Red stands for caution. Fire is red. That’s about as cautionary as you can get in the world of colors. As for yellow for “stop if you can, it’s about to turn red,” that makes sense, too. There’s yellow in fire, too. Come to think of it, fire is usually a mixture of red and yellow. So far, so good.
But then we come to green for “go.” Why not blue? Or purple? Why green?Continue reading Why Are Green Lights Green?