On December 9, 1868 the first, non-electric gas-lit traffic lights were installed outside the Houses of Parliament in London to control the traffic near Parliament Street. Three semaphore arms with red and green gas lamps for night-time use were operated by a police constable.

Successful in controlling traffic, its operational life was brief — it exploded less than a month later as a result of a gas pipe leak, killing or injuring the policeman. The concept was abandoned until electric signals became available.

In 1912, an electric traffic light was developed by Lester Wire, a policeman in Salt Lake City, Utah, who also used red and green lights. On this day, Aug. 5, 1914, the American Traffic Signal Company installed a signal system on the corner of East 105th Street and Euclid Avenue in Cleveland, Ohio. It had two colors, red and green and a buzzer based on the design of James Hoge, to provide a warning for color changes. The first four-way traffic light was created by police officer William Potts in Detroit, Michigan in 1920. Ashville, Ohio claims to have the oldest working signal in the United States, used at an intersection of public roads from 1932 to 1982 when it was moved to a local museum.

After witnessing an accident between an automobile and a horse-drawn carriage, African-American inventor, Garret Morgan, became one of the first to file a U.S. patent for a traffic signal, and his three-position signal became the ancestor of today’s yellow warning light position commonly seen around the world today.

The first interconnected traffic signal was installed in Salt Lake City in 1917, with six connected intersections controlled simultaneously from a manual switch. Los Angels installed its first automated traffic signals in October 1920 at five locations on Broadway. Automatic control of interconnected traffic lights was introduced March 1922 in Houston, Texas. The Acme semaphore traffic lights were often used in Warner Bros. Looney Tunes and Merrie Melodies cartoons for comedic effect due to their loud bell.