The traffic light doesn’t have a single “creator” – it evolved in stages, with several key inventors along the way.

Quick Scoop: Who made the traffic light?

1. The very first traffic signal (1868)

  • In 1868, John Peake Knight , a railway signaling engineer in London, designed what is considered the world’s first traffic signal.
  • It was installed near the Houses of Parliament in London and used semaphore arms by day and red/green gas lamps by night.
  • A police officer operated it manually, and it was short‑lived after a gas explosion badly injured the operator.

In simple terms: Knight created the first “traffic light” idea, but it was mechanical and gas‑powered, not electric.

2. First electric traffic lights (1910s)

  • In 1912, Lester Farnsworth Wire , a police officer in Salt Lake City, built one of the first electric traffic lights using red and green lights on a pole in the middle of an intersection.
  • His design had to be switched manually but introduced the familiar electric red/green system that looks much closer to what we see now.

3. The “first electric traffic signal” credit

  • Many histories give the “first electric traffic signal” credit to James Hoge , whose system was installed in Cleveland in 1914.
  • Hoge’s design showed the words “STOP” and “MOVE” on illuminated signs and was wired so police and fire departments could change the timing in emergencies.

4. Adding automatic control and more colors

  • William Ghiglieri (San Francisco) patented one of the first automatic red–green electric signals in 1917; they could be run automatically or manually.
  • In 1920, William Potts , a Detroit police officer, created one of the first four‑way, three‑color electric traffic lights, adding the amber/yellow light to manage busy intersections more safely.

5. Garrett Morgan and the three‑position signal

  • In 1923, Garrett Morgan patented a T‑shaped electric traffic signal that introduced a third “caution” position , effectively an early form of the yellow phase.
  • His design stopped traffic in all directions briefly so intersections could clear, which made crossings safer and was cheaper to produce, helping spread the use of signals.

So, who “made” the traffic light?

You can think of it like this:

  • First traffic signal (gas, mechanical): John Peake Knight, London, 1868.
  • First practical electric red–green lights: Lester Wire, Salt Lake City, 1912.
  • First widely credited electric signal system: James Hoge, Cleveland, 1914.
  • First three‑color, four‑way electric light: William Potts, Detroit, 1920.
  • Influential three‑position/yellow‑style design: Garrett Morgan, 1923.

In everyday answers, people often name John Peake Knight (first signal) or Garrett Morgan / William Potts (shaping the modern three‑color system), but the modern traffic light is really the result of several inventors over about 60 years.

Information gathered from public forums or data available on the internet and portrayed here.