It’s amazing how a fun childhood game like Red Light/Green Light relates to some crucial decisions when you’re out on the road. While this schoolyard game honed your reflexes and attention as a child, those reactionary responses can mean the difference between life and death behind the wheel. To help keep you safe, the stop sign has evolved over the years with a design that gets your attention more easily so you can react more quickly.
The first stop signs were posted in Michigan in 1915. Originally, they were square-shaped, measuring 24 by 24 inches and featured black letters on a white background. These plain signs may have been adequate at first since there weren’t many cars on the road, but by the 1920s, the number of cars on the road began to increase and the U.S. standardized all stop signs to the octagonal shape that we still see today.
Why an octagon? The American Association of State Highway Officials saw a few key advantages to giving the stop sign its unique shape. First, the octagonal shape makes it easy for drivers traveling in the opposite direction to recognize the sign from the back, which helps prevent confusion at intersections. Second, since the original stop signs weren’t reflective, the AASHO needed a design that could be easily recognizable at night.
Stop signs are retroreflective, which means that if your headlights shine on them, light will be reflected back toward you.
While the stop sign’s shape has remained the same since the 1920s, it wasn’t always red like the one we see today. Multiple revisions were made, but up until the mid-1950s, stop signs generally featured a yellow background with black letters and a black outline. In 1954, the stop sign got a makeover, resulting in its current look, which features a white outline and lettering with a red background.
It’s understandable that suddenly changing the look of a traffic sign could cause some confusion (imagine if speed limit signs were suddenly blue), but the move to a red sign was a logical one. Since stop lights are red, changing the sign’s color to red reinforced the notion that a red sign or light means “stop.”
Today’s stop sign stands approximately 7 feet off the ground and measures 75 cm (around 29.5 inches) across from one flat side of the red octagon to the other. The white border of the stop sign is 2 cm wide and the word STOP is written in capital letters that are 25 cm (approximately 10 inches) tall. Stop signs are also retroreflective, which means that if your headlights shine on them, light will be reflected back toward you. On roads that have more than one lane, stop signs are slightly larger, measuring about 95 cm (around 37 inches) wide.
The familiar red octagonal shape of stop signs is now the standard in most of the world. Countries like China, Columbia, Iran, Ireland, Korea and Taiwan all use different languages, but that red octagon with a white border means the same thing in all of them — stop.