Why Stop Signs Used To Be Yellow

In the world of signals, it’s undisputed that red means stop. From red traffic lights to “prohibited” signs to, of course, the stop sign itself, red grabs your attention and sends a message to stop.

But you probably didn’t know that red has only been the stop sign standard for about 70 years. Before then, the octagonal traffic sign was yellow, with the word STOP in black letters. It wasn’t until 1954 that the stop sign became the bright red color, adorned with white letters, that we know today.

The History of the Stop Sign in the U.S.

In the early 20th century, stop signs weren’t any specific color or even shape. Understandably, the lack of standardization confused drivers, so the American Association of State Highway Officials (AASHO) convened in 1922 to select a standard design. This is how the octagonal shape came to be.

The AASHO wanted to choose a shape that drivers coming in the other direction would recognize and know oncoming traffic had a stop sign. They chose a yellow design with black letters, figuring the colors would grab drivers’ attention.

Yellow wasn’t their first choice, however. They actually considered making stop signs red, since red already meant “stop” on electric traffic lights, invented in 1912. The problem was, back then, all red dyes faded over time.

Changes in Sign Making

By the 1950s, though, sign makers were using a fade-resistant porcelain enamel, eliminating the problem. California made the switch first. Based on that, in 1954 the Joint Committee on Uniform Traffic Control Devices declared that, henceforth, stop signs would be red with white lettering.

According to the revised manual: “The recent achievement of dependable red finishes, available in competitive materials, has made the red sign practical, and the Joint Committee has recognized an apparent trend of opinion among highway departments by accepting the red sign as the sole standard, eliminating the yellow sign and its variants with contrasting panels.”