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Ohio inventions and firsts · Invention · 1923

Three-position traffic signal

Garrett Morgan, a Cleveland inventor, patented a manually operated crank signal with semaphore arms whose vertical position stopped traffic in all directions before the right-of-way changed. He sold the patent to General Electric (reported $40,000).

At a glance

Year
1923
By
Garrett A. Morgan
Place
Cleveland, Cuyahoga County ZIP 44114 · Cleveland · Cuyahoga County
Patent
US 1,475,024 US 1,475,024 (filed Feb 27 1922, granted Nov 20 1923)

The story

As cars multiplied in the early 1920s, intersections became dangerous. Signals of the day only showed stop or go, with nothing to warn drivers that the right of way was about to change. Garrett Morgan, a Cleveland inventor, is said to have been moved to act after seeing a collision at a crossing.

Morgan's signal was hand-cranked and had moving arms that said stop and go. His patent was granted on November 20, 1923. What set it apart in his design was a third position that halted traffic in all directions, giving pedestrians and cross traffic time to clear before the next direction moved.

He sold the rights to General Electric for $40,000. Signals were already in use before his: London had one in 1868, Salt Lake City had an electric one in 1912, Cleveland put in one in 1914, and in 1920 William Potts of Detroit made a three-color light with an amber caution light. Morgan's own design was not a color light, so the claim that he invented the modern traffic light is too strong.

Morgan was born in Kentucky on March 4, 1877, had only a sixth-grade formal education, and kept studying on his own. He died in Cleveland on July 27, 1963.

Timeline

  • 1868-12: The first traffic signal, with semaphore arms, appears at Parliament Square in London. (London, England) source
  • 1912: Lester Wire, a Salt Lake City policeman, develops an electric traffic light. (Salt Lake City, UT) source
  • 1914-08: An electric signal is installed at East 105th Street and Euclid Avenue. (Cleveland, OH) source
  • 1920: William Potts creates a three-color light in Detroit. (Detroit, MI) source
  • 1923-11-20: Morgan's traffic signal patent is granted; he sells the rights to General Electric for $40,000. (Cleveland, OH) source
  • 1963-07-27: Morgan dies in Cleveland. (Cleveland, OH) source

What it changed

  • General Electric paid $40,000 for the rights.
  • Morgan's all-direction stop position gave drivers a pause before the right of way changed.

Why it matters

Added the all-stop interval; patent sold to General Electric.

Who gets the credit is disputed

The Ohio claim. Garrett Morgan, a Cleveland inventor, patented a crank-operated signal whose vertical position stopped traffic in all directions before the right-of-way changed. He sold the patent to General Electric.

The other claims. Traffic signals existed before him: London in 1868, Salt Lake City in 1912 (Lester Wire), Cleveland in 1914 (Hoge) and Detroit in 1920 (William Potts, with three colors). Morgan's claim rests on the all-stop interval.

Places in Ohio to see

Further reading

Sources

Confidence. High: the main facts were confirmed in sources we opened.