William Potts (1883–1947) was born in Michigan and served as a Detroit Police officer from the age of 17. He is credited to invent a three-way traffic light in 1920. Officially, he did not get the patent for his invention but since the legal battle started between the manufacturers of the traffic light, The United States District court certified Potts to have started the use and construction of the first four-way traffic signal.
William Potts invented the yellow or the amber light, so that the traffic police might not have to switch the red and the green signal. It was this achievement in managing the ever increasing traffic on the roads that he was promoted to the post of superintendent, signal person police, Detroit. Potts installed automatic light signal system in 15 towers of the traffic signal in the Detroit. He retired from police services in 1939 and joined Safety and Traffic department of the Automobile Club of Michigan.
