20 Things Turning 100 in 2020

The first tri-color, four-way traffic light was created in 1920.

William Potts, a Detroit police officer, created the first three-color, four-directional traffic signal. Prior to Potts’ invention, the traffic light used only red and green lights.

The yellow light was new at the time and became the standard in all traffic signals by the mid-1930s, according to the The Henry Ford Museum.