It’s the 101st anniversary of the first electric traffic signal system. On August 5, 1914, in Cleveland, Ohio, engineers installed a pair of green and red lights facing each side of a four-way intersection — a simple experiment that has since shaped roads around the world.
But this simple invention marks a key moment in the largely forgotten transformation of roads during the 20th century. For most of history, roads have been chaotic, shared public spaces, packed with horses, handcarts, merchants, pedestrians, and children. As much as any other invention, the traffic signal gave rise to the carefully controlled, highly automated thoroughfares we think of as roads today.
Why we needed traffic signals
Horses, carriages, carts, streetcars, and pedestrians had been navigating busy intersections for years — but they moved pretty slowly, which meant turn-taking and other informal driving customs generally worked fine.
How the new traffic signal worked
The system installed in Cleveland wasn’t the first we’d recognize as a traffic signal today. London’s 1868 signal used semaphore arms combined with red and green gaslights during nighttime — colors that had long been used to mean “stop” and “go” by various sorts of industrial machinery. It exploded after about a month of use, though, injuring the operator.
Then, in 1912, police officer Lester Wire built and installed a device in Salt Lake City that “looked like a large birdhouse with lights dipped in green and red paint and placed into circular holes on each side,” according to the Salt Lake Tribune — but it, too, was short-lived, and Wire seems to have gone off to World War I instead of securing a patent.
Finally, in 1914, at the corner of Euclid Avenue and East 105th Street — one of the busiest intersections in Cleveland — the city hired the American Traffic Signal Company to implement an enduring system that had been patented by Clevelander James Hoge a year earlier.
(Chicago in 1912)