Most prominently, the inventor Garrett Morgan has been given credit for having invented the traffic signal based on his T-shaped design, patented in 1923 and later reportedly sold to General Electric.

Who invented the traffic light in 1920?

1920 — William Potts, a Detroit policeman, invented the first four-way and three-colored traffic lights. He introduced yellow lights to indicate the light would change soon. Detroit became the first city to implement the four-way and three-colored traffic lights.

When was the yellow traffic light invented?

1923: Three-position traffic signals get patented

The yellow light made intersections safer than the old stop and go system. The new design was inexpensive enough that it allowed the installation of a lot more lights. Morgan sold the patent to General Electric—and the spread of the traffic light was green lighted.