For drivers in many parts of the globe, the red, yellow, and green sequence of traffic lights has become an instinctual part of how we move through the world. But why these three colors? How did they come to govern the movement of billions of people across the planet every day? As it turns out, there are a few factors in play, including the history of transport, color psychology, and basic physics.  Credit: © Barry Winiker—Stockbyte/Getty Images  Red Lights and Railroads The colors used in traffic lights today were not invented for roads. They were ...Read More