When Were Traffic Lights First Used?
You may think that the familiar red-green, traffic signal is a product of the automotive age. But actually, the first traffic signal was erected in 1868, in London, to assist pedestrians in crossing a busy intersection of George and Bridge Streets to the British Houses of Parliament. They were invented by J P Knight. The hand-operated device had revolving red and green gas lamps.
Unfortunately, the gas apparatus exploded after short use, injuring the constable assigned to operate it. Electric red and green traffic lights, designed to control automobile traffic, were first put into use in Cleveland, Ohio in 1913. James Hoge patented (1,251,666) manually controlled traffic lights in 1913, which were installed in Cleveland, Ohio a year later by the American Traffic Signal Company.
Hoge’s electric-powered lights used the illuminated words “stop” and “move”. Around 1920, William Potts a Detroit policeman, invented (unpatented) several automatic electric traffic light systems including an overhanging four-way, red, green, and yellow light system. The first to use a yellow light.