The world’s first traffic lights were installed near London’s House of Commons in 1868. J. P. Knight invented them. William Ghiglieri of San Francisco, California, patented perhaps the first automatic traffic signal using coloured red and green lights in 1917. Ghiglieri’s traffic signal had the option of being either manual, or automatic.
In 1920, William Potts, a Detroit Policeman, invented an automatic overhanging electric traffic light system with red, green, and yellow Colours.
Posted by :- Dr. Prashant