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Fascinating facts about the invention
of the
Traffic Light by William L. Potts in 1920.
TRAFFIC LIGHT
AT A GLANCE:
Police Officer William L. Potts of Detroit, Michigan, decided to do something about the problem caused by the ever increasing number of automobiles on the streets. What he had in mind was figuring out a way to adapt railroad signals for street use. Potts used red, amber, and green railroad lights and about thirty-seven dollars worth of wire and electrical controls to make the world’s first 4-way three color traffic light. It was installed in 1920 on the corner of Woodward and Michigan Avenues in Detroit. Within a year, Detroit had installed a total of fifteen of the new automatic lights.
 
THE STORY
RELATED INFO
BOOKS
WEB SITES
DID YOU KNOW?
Invention: Traffic Light
Potts Traffic Light photo courtesy The Henry Ford, Greenfield Village
Function: noun / trsffic signal / stoplight
Definition: A road signal for directing vehicular traffic by means of colored lights, typically red for stop, green for go, and yellow for proceed with caution.
Patent: As a government emplyee Potts could not patent his invention.
Inventor: William L. Potts
William Potts photo courtesy Mr. Trafficlight
Criteria: First practical. Modern prototype.
Birth: Unknown
Death: Unknown
Nationality: Unknown
Milestones:
1918 U.S.Patent # 1,251,666 issued January 1, to J.B. Hoge of Cleveland, OH
1919 U.S.Patent # 1,307,544 issued June 24,  to Oscar A. Erdmann of Detroit, MI
1920 William Potts invents and installs a three color, four direction taffic light in Detroit, MI
1923 U.S.Patent # 1,475,024 issued November 20, 1923 to Garrett Morgan for traffic signal
ARYs: traffic light, traffic signal, stop light, William Potts, Garrett Morgan, J Hoge, Oscar Erdmann, history, invention, stroy, facts, biography, inventor.
Story:
Even during the horse and buggy days, traffic in big cities was often heavy. Police officers had to be stationed full time directing traffic at busy intersections.
 
The world’s first traffic light came into being before the automobile was in use, and traffic consisted only of pedestrians, buggies, and wagons.  Installed at an intersection in London in 1868, it was a revolving lantern with red and green signals.  Red meant "stop" and green meant "caution."  The lantern, illuminated by gas, was turned by means of a lever at its base so that the appropriate light faced traffic.  On January 2, 1869, this crude traffic light exploded, injuring the policeman who was operating it.

With the coming of automobiles, the situation got even worse. Police Officer William L.  Potts of Detroit, Michigan, decided to do something about the problem.  What he had in mind was figuring out a way to adapt railroad signals for street use.  The railroads were already utilizing automatic controls. But railroad traffic traveled along parallel lines.  Street traffic traveled at right angles. Potts used red, amber, and green railroad lights and about thirty-seven dollars worth of wire and electrical controls to make the world’s first 4-way three color traffic light. It was installed in 1920 on the corner of Woodward and Michigan Avenues in Detroit. Within a year, Detroit had installed a total of fifteen of the new automatic lights.

At about the same time, Garrett Morgan of Cleveland, Ohio realized the need to control the flow of traffic. A gifted inventor and reportedly the first African American to own an automobile in Cleveland, Ohio, he invented the electric automatic traffic light. Though it looked more like the semaphore signals you see at train crossings today.

Many others had obtained US Patents for Traffic Signals, some as early as 1918. But Morgan's Patent was purchased by General Electric Corporation and provided the protection they needed to begin building a monopoly on traffic light manufacture.

TO LEARN MORE

RELATED INFORMATION:
Garrett Morgan Biography   from The Great Idea Finder
Transportation History   from The Great Idea Finder

ON THE BOOKSHELF:
Eureka!: An Illustrated History of Inventions From the Wheel to the Computer (Limited Avail.)
by Edward De Bono / Hardcover - 248 pages (1974) / Thames & Hudson

A marvelous array of history's and prehistory's most important and intriguing inventions.
The Kid Who Invented the Popsicle: And Other Surprising Stories About Inventions
by Don L. Wulffson / Paperback - 128 pages (1999) / Puffin

Brief factual stories about how various familiar things were invented, many by accident, from animal crackers to the zipper.

Why Didn't I Think of That?: Bizarre Origins of Ingenious Inventions We Couldn't Live Without
by Allyn Freeman, Bob Golden / Paperback: 260 pages / John Wiley & Sons; (September 1997)
Filled with wacky and fascinating facts, awe-inspiring success statistics, and rags-to-riches stories, Chronicles the odd origins behind 50 famous inventions and reveals the business side of each product's actual production, marketing, and distribution.
Garrett Morgan: Inventor
by Garnet Jackson / Paperback - 26 pages / Dearborn Financial Publishing (1992)
A brief biography of an African American inventor that describes, in rhyming text, how his lifelong interest in machines led to the invention of the traffic signal.


ON THE WEB:
William Potts Traffic Light
Although Potts' achievement seems to not have been recognized at the time, a United States Court decision in 1928 established that he was, indeed, the inventor of the first 4-way, three-color signal.
(URL: www.signalfan.com)

Four-Way Traffic Signal
The intersection of Woodward Avenue and Fort Street (or Woodward and Michigan Avenue; both sites are recorded) in Detroit was the site of the world's first four-way traffic stop, which was put there in 1920. The stoplight had twelve bulbs and was manually operated.
(URL: www.michiganhistorymagazine.com/features/michweek/splash.html)

Garrett Morgan's Traffic Light
Invention of the traffic light according to the U.S. Department of Transportation.
(URL: education.dot.gov/aboutmorgan.html)
Mr. Trafficlight
The first traffic lights had only four-inch lenses and the shell was wood with a tin cover. An original lamp was presented to Henry Ford’s collection of Americana at the Edison Institute, Greenfield Village, in 1938.
(URL: www33.brinkster.com/iiiii/trfclt/mrtrafficlight/mrtrafficlight.html)
The Hery Ford - Greenfield Village
Experience 300 years of history as the sights, sounds and sensations of America’s past come alive!
(URL: www.thehenryford.com/village/default.asp)
Why Are Traffic Signals Red, Green and Amber?
In 1920 Police Officer William Potts addressed the chaotic traffic of Detroit, Michigan, by co-opting the red, amber, and green automatic traffic light system used on railroads.
(URL:
ask.yahoo.com/20031023.html)
Switching Signals
As traffic jams and headaches increase, inventors are continuing to work hard to make travel more safe and efficient.
(URL: homepages.cae.wisc.edu/~wiscengr/didyouknow/Traffic%20Lights/traffic_lights.shtml)
The Traffic Signal Museum
This site displays a private collection of over 75 vehicle and pedestrian traffic signals. Most people don't realize how many different types and makes of signals there are. The Traffic Signal Museum is the name of the site, it is not a real museum.
(URL: www.trafficsignalmuseum.com/)
Invention Dimension - Inventor of the Week
Featured Garrett A. Morgan (1877-1963) for his invention of the The Gas Mask.
(URL: web.mit.edu/invent/iow/morgan.html
)

DID YOU KNOW?

  • The Morgan traffic signal was a T-shaped pole unit that featured three positions: Stop, Go and an all-directional stop position. This “third position” halted traffic in all directions to allow pedestrians to cross streets more safely.

  • Morgan's traffic management device was used throughout North America until it was replaced by the red, yellow and green-light traffic signals currently used around the world.

  • Morganr sold the rights to his traffic signal to the General Electric Corporation for $40,000.

  • Shortly before his death, in 1963, Morgan was awarded a citation for his traffic signal by the United States Government.

  • Garrett Morgan earned US Patent No.1,475,024 issued November 20, 1923 fot his traffic signal.

Reference Sources in BOLD Type This page revised November 13, 2006.
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