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I guess it’s one of those things that I’ve just taken for granted. I mean, for a traffic signal enthusiast, we’ve always known that red is on the top and green is on the bottom. There are a couple of exceptions that have to do with some interesting history. But every other vertically-mounted signal in the United State is set up with the red on top.

With the increasing popularity of motor travel in the early 1900s, many firsts had emerged. The first center line appeared, the first stop sign popped up, the first official route signs were laid out, and the first traffic signal became part of the landscape.

By 1927, a committee called the American Society for Municipal Improvements recommended that red be on top and green be on the bottom. These requirements were published in the 1930 urban MUTCD. So basically, for the last 90 years, traffic signals are supposed to have red on top and green on the bottom.

But why do I see so many misconfigured traffic signals? I’m not referring to the ones on the road. There is one exception, but I’ll get to that later. I’m referring to illustrations, toys, and models. Not uncommon is the occasional up-side-down Signal Ahead road sign. Yes! Real road signs placed by workers who are should know better!

I’d like to take a poll some day and randomly go up to people asking them what color is on top. It wouldn’t surprise me to hear a few people tell me that green is on top. I’ll get back to you on that when I actually have results.

However, here are a couple of exceptions to the red-on-top rule.

The W.S. Darley C-811

3-bulb W. S. Darley traffic signal with built-in controller, circa 1938In the late 1920s, W.S. Darley & Company began manufacturing signals that were purposefully configured with red on top for main street while the cross street had green on top. The design acted as a cost-saving measure for smaller towns that wanted to save money on their traffic control devices. The signals worked by utilizing a single bulb illuminating lenses for each section in all four directions. For example, the top would have red lenses for the main street and green lenses for the cross street. That single bulb lit up all four direction. When the light on the bottom would illuminate and change to green for the main street, the cross street then had a red on the bottom for them. These signals even had a built-in electro-mechanical controller in the base of the signal that ran the show. Pretty sweet design. Three bulbs, minimal wiring, simple design. But eventually these signals went the wayside.

Perhaps red on top was merely a “suggestion” and not set-in-stone?

Tipperary Hill

Tipperary Hill Traffic SignalThe only red-on-top signal that still exists in the United States hangs in an intersection in the Tipperary Hill section of Syracuse, New York. As a predominantly Irish community, the colors of the traffic signal represented British (red) superiority over the Irish (green). That didn’t go over well. A group of “stone-throwers” began hurling rocks as the signal. Since plastic lenses didn’t exist in the 1920s, the glass did not fare well.

After repeated replacements of the lenses, the city relented and changed the signal so that the green was at the top. It’s been like that ever since.

So despite the limited history of inverted colors on traffic signals, and the fact that many of us see traffic signals every day, why do I see so many incorrectly represented signals? My guess is that people just don’t notice or care to notice what color is on top. They just know red means stop and green means go.

And yellow means go faster.

scroll to topThe green lens looks blue when not illuminated by an incandescent light bulb.