* The amber light was introduced in the 1920s.

With only a red and green signal, drivers didn’t have an interval to slow down. On busy and noisy intersections, that caused plenty of accidents. In 1920, the amber/yellow signal was added to warn drivers of the impending stop. Of course, today some drivers consider the amber light a signal to go even faster to try to beat the red.

* You can see the red light faster than you can see the green light.

The traffic light was modeled after signals used on railroad tracks and crossings. There’s little evidence as to why the colors red and green were initially chosen to represent “stop” and “go” – but we now have a scientific rationale for that decision. Because red light has a longer wavelength than green, it can be seen from farther away. The sooner you see the light, the sooner you hit the brakes.

* The traffic light continues to evolve.

Most cities these days use cutting-edge technology and energy-saving LEDs that are controlled by massive central traffic management centers. Future traffic lights will sync with our phones… even talk to us, display news headlines, and communicate with our cars’ navigation systems, telling the car how fast to go to avoid red lights.