First Tri-Color, Four-Directional Traffic Signal, 1920

Potts, William L., 1883-19471920

The Henry Ford

The Henry Ford
Dearborn, MI, United States

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Detroit traffic officer William Potts created this three-color, four-way traffic signal in 1920. Previous illuminated signals used only red and green lights. The addition of an amber "caution" light made driving safer and the three-color signal became the standard by the mid-1930s. This first traffic light was installed at Woodward Avenue and Fort Street in Detroit, Michigan.

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  • Title: First Tri-Color, Four-Directional Traffic Signal, 1920
  • Creator: Potts, William L., 1883-1947
  • Date Created: 1920
  • Location: United States, Michigan, Detroit, Woodward Avenue
  • Subject Keywords: Automobiles, Firsts, Traffic, Safety, Cars, Traffic signals
  • Type: Objects
  • Contributor: The Henry Ford
  • Original Source: Digital Collections
  • Patent Date: 1920
  • Object Name: Traffic signal
  • Object ID: 38.537.1
  • Inventor: William Potts
  • Invention: Traffic Signal
  • Image ID: THF151126
  • Field: Transportation
  • Credit: From the Collections of The Henry Ford. Gift of City of Detroit Police Department.