While it was an American policeman Lester Wire, in Utah, who first developed an electric traffic light in 1912 and used red-green lights, the American Traffic Signal Company installed a traffic signal system on the corner of East 105th Street and Euclid Avenue in Cleveland, Ohio two years later on 5 August 1914.

However, the first, non-electric, gas-lit traffic lights were installed outside the Houses of Parliament in London on 9 December 1868 to control the traffic in Bridge Street, Great George Street and Parliament Street. They were promoted by the railway engineer J P Knight and constructed by the railway signal engineers of Saxby & Farmer.

The design combined three semaphore arms with red and green gas lamps for night-time use, on a pillar, operated by a police constable. The gas lantern was manually turned by a traffic police officer, with a lever at its base so that the appropriate light faced traffic.

Although it was said to be successful at controlling traffic, its operational life was brief. It exploded on 2 January 1869, as a result of a leak in one of the gas lines underneath the pavement, injuring or killing the policeman who was operating it. With doubts about its safety, the concept was abandoned until electric signals became available.