Earnest Sirrine of Chicago, Illinois patented first automatic street traffic system in 1910.

Earnest Sirrine of Chicago, Illinois patented (No. 976,939) perhaps the first automatic street traffic system in 1910. 

The device used two separate display arms that rotated on an axis between two fixed positions. The display arms were arranged as a cross with one display continually offset from the other by 90-degrees. In place of red and green lights, Sirrine’s “street traffic system” used the non-illuminated words “stop” and “proceed.”