Celebrated on August 5th
On Aug. 5, 1914, a four-way traffic signal was installed in the busy Cleveland, Ohio, intersection of Euclid Avenue and East 105th Street. Why was this seemingly mundane event 101 years ago important? Because it was the first electric traffic signal that resembles what's seen all over the world today. It wasn't automatic; it was operated by a police officer in a booth. And there were only red and green lights. But for all intents and purposes, it was the first-ever modern traffic light.
All traffic signal lights define : Red means Stop Red is a universal sign of danger. Plus this color is visible even in harsh conditions like fog, rain or in smoke. Yellow indicates to Wait. Yellow is a color that defines caution, plus it is made by the super position of red and green, hence, an obvious choice! Green means Go. It is specifically chosen because it is considered as a calm color. Moreover, this color is easily distinguished from the other two colors and can be seen easily.
The first-ever recorded use of stop signs was in Detroit, Michigan, in 1915, and they were originally yellow with black lettering. They were eventually standardized and adopted the world over by the 1968 Vienna Convention on Road Signs and Signals.