Ever wonder how a traffic light works" Today, they’re mostly computer controlled, just like everything else. But up until recently they were in large part mechanical, each intersection timed by an ingenious bit of circuitry that, when properly set up, allowed for complex traffic flows from all directions.
But if you go back further, all the way to the 1930s, the state of traffic lights was almost bafflingly complex. Before the traditional red-yellow-green three-light array was standardized across the United States, seemingly every town in America had a different system of traffic signals. And if you weren’t versed in a town’s particular choice of signal, you were in for a hell of a time.
That’s what we learned from the Jam Handy film from 1937 embedded below, explaining both the traffic signal’s mechanical design and the many varieties of signals you might come across as you drove through this great nation in that era. In some arrangements, the yellow light meant go; in others, it meant stop. Some towns used a clockwork device with no lights at all, while others used the semaphore system, with Stop and Go placards rotating in and out of a housing like mechanical arms. It’s dizzying enough to make you appreciate the predictability of the red-on-top three-light signal, where green is go, yellow means slow down, and red is stop. Though if you’re driving through the Tipperary Hill neighborhood of Syracuse, New York, you’l...