Invention of the Traffic Light

On December 10, 1868, the first traffic lights were installed outside the British Houses of Parliament in London, by the railway engineer J. P. Knight. They resembled railway signals of the time, with semaphore arms and red and green gas lamps for night use. The gas lantern was turned with a lever at its base so that the appropriate light faced traffic.

The modern electric traffic light is an American invention. As early as 1912 in Salt Lake City, Utah, policeman Lester Wire invented the first red-green electric traffic lights. However, it must be noted that this claim is also made by Garrett Morgan. Many have claimed that Morgan did indeed invent the modern traffic light, but was refused the credit on the grounds that he was a black man.

Unfortunately for Morgan, there is no evidence to support the claim that Morgan’s traffic signal was ever put into service. Despite claims on various websites as well as in print that Morgan’s invention was used throughout North America, the absence of his signal in 1920’s photographs and news articles suggests that it was not installed in large numbers, if it was installed at all. It remains a bit of a question.

On August 5, 1914, the American Traffic Signal Company installed a traffic signal system on the corner of East 105th Street and Euclid Avenue in Cleveland, Ohio. It had two colours, red and green, and a buzzer to provide a warning for colour changes.

The colour of the traffic lights representing stop and go might be derived from those used to identify port (red) and starboard (green) in maritime rules governing right of way, where the vessel on the left must stop for the one crossing on the right.