The colour-wheels on the bus don’t go round and round anymore.

As the kids go back to school, let’s look back at how the school bus got its permanent pigment.

Andrew Samm
5 min readSep 6, 2023

6th September 2023

The promise of crisp air, pumpkin spice… everything, and the rustle of leaves underfoot is just around the corner. But, dear readers, as the days start growing shorter and the first hints of autumnal colours are beginning to grace the trees, there’s a hue that shines even brighter than the fiery reds and oranges of fall foliage. It’s the colour of school bus yellow, and the story behind it, like a ray of sunshine, will warm your heart as we bid a fond farewell to the lazy days of summer and pack the kids back off to school.

In the late 1930s school US school buses were like chameleons, donning various colours that would blend into the tapestry of traffic. Safety concerns were growing, and accidents involving school buses were far too common. Frank W. Cyr, an educator and professor at Teachers College, Columbia University, saw an opportunity to make a change.

In 1939, Cyr orchestrated a ground-breaking conference that united educators, paint experts, and transportation officials from across the United States. Their mission? To craft a standardised colour that would enhance school bus safety. Cyr’s vision was as bright as a sunny autumn day: he aimed to design a colour that could be seen from afar and under any lighting conditions. The outcome? “National School Bus Chrome,” a shade of yellow that captured the essence of safety and was destined to become an iconic colour.

Frank W. Cyr at the wheel of a school bus in Manhattan, in 1989, at an event to celebrate the 50th year of the yellow school bus. (Credit: Chester Higgins Jr./The New York Times)

The black lettering on the chosen hue was the most legible in semi-darkness in the early morning and late afternoon when children were en route to and from school. Further, in recent years, scientists have found that people can see yellow objects in their peripheral field 1.24 times better than red, and, unlike red, yellow is more detectable in a dark environment and at a distance. The black lettering coupled with school bus yellow is the easiest colour combination for drivers to see, and hence this colour was also chosen for safety.

“The colour they selected was and remains ‘national school bus chrome,’” said Bob Riley, executive director of the National Association of State Directors of Pupil Transportation Services. “I don’t know why the word ‘chrome’ was in there, but it has something to do with the makeup of that paint.”

The most recent version of the standards, approved in 2010, calls the colour “national school bus yellow,” and Mr. Riley said there is a specific formula for it.

“I’ve seen it,” he said, alluding to the formula. “We used to have it on our Web site. I think we dropped it off the Web site because nobody ever asked for it.” But, he added, “You can’t buy a bus that doesn’t meet that formula.”

The school-bus conference introduced several specifications that have undergone revisions over time. However, the yellow, has remained unchanged, despite originating from an era predating the vibrant palettes famously associated with artists such as Andy Warhol and Peter Max.

In fact, the school bus design itself was patented in 1938 (US 2,112,150 A — ‘School bus’), (it wouldn’t be a Patently blog without mentioning a patent) but colour or even safety in general were not considered key features at the time; the patent instead focusses on “a bus body which is particularly strong and which is particularly simple in construction and may be readily and economically built.

fig. 1 US 2,112,150

“If they had to do it today, who knows if it would be the same, because now they have brighter, more noticeable things,” Mr. Riley said. “Think of the vests highway workers wear. Obviously, they’re even more noticeable than national school bus chrome yellow. But the rationale for maintaining that colour is its universal acceptance. We’ve all been born and raised knowing what that is.”

It also wouldn’t be a Patently blog without a nerd-friendly section, so getting technical for a minute, ‘School bus yellow’ is a colour standardized by none other than the American National Standards Institute (ANSI). The ANSI sets the standard for the hex and RGB values that make school bus yellow the unmistakable shade it is.

For those tech-savvy readers itching for the specifics, the hex code is #FFD100, while the RGB values are R: 255, G: 209, B: 0. These values ensure that school buses shine like beacons of safety, no matter the season.

Now, we’ve spent all this time referring to the colour as a ‘yellow’, but school bus yellow is technically considered to be neither pure yellow nor pure orange, but a mix of the two, and it is the closest to the colour of a flesh of a mango. This ‘controversy’ reminds us of the arguments we had during Wimbledon; are tennis balls yellow or green? If you want to find the answer check out one of our earlier blogs “New balls please”.

We’re DYE-ing to know what HUE think.. what’s your favourite autumnal colour? Let us know via the socials.

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Andrew Samm

Certified QPIP, Patent data expert & tech enthusiast After work I'm a Spurs fan, Tigers fan, AFOL, Yognaught, GandDiva, Potterhead, and a lover of ATLA & LOTR