Harriss and Freedlander were the first to bring the traffic signal to New York City, but they were certainly not its inventors. Signaling systems had been in use on railroads across Britain and America throughout much of the 19th century; by 1868, a British railroad engineer named John Peake Knight had modified one such system for use on city streets. Installed outside London’s Houses of Parliament and operated manually by a traffic cop, Knight’s traffic signal used semaphore arms—colored posts that can be adjusted to different angles—borrowed from the railroad system. At night, these were replaced with gas-powered red and green lamps.
Unfortunately, the world’s first traffic signal was short-lived; less than one month after it was installed, it exploded, killing a policeman.
It was the advent of widespread electricity and the rise of the motor vehicle that led to the traffic signaling systems we’re more familiar with today. The very first known electrical system—the antecedent that Harriss and Freedlander based their later designs on—was created by Lester Farnsworth Wire, a Salt Lake City police officer in 1912. His design was simple: He created a wooden box resembling a bird house, and built a pole on which to mount it. He then dipped light bulbs in red and green paint, mimicking the colors used for railroad lights, and connected the box to the overhead wire system used for trolley cars. It was controlled by a switch that was operated by a policeman nearby.