What Makes School Buses Yellow?

Every single school bus in the United States is coated in the same signature shade, known as 'National School Bus Glossy Yellow.' However, this wasn't always the case.

A hundred years ago, children were transported to school by a variety of makeshift vehicles. With no federal regulations in place, it was left to states or individual school districts to employ buses, trucks, and even horse-drawn wagons for the task.

Frank Cyr was dissatisfied with the existing system. In the 1930s, Cyr, a professor at Teachers College, Columbia University, and a proponent of rural education, traveled across the country conducting research on school transportation. 'In many cases, standards have been set up by more or less hit-and-miss methods,' Cyr remarked in a New York Times article. He concluded that action was needed to ensure the safety of America's schoolchildren.

In 1939, Cyr organized a pivotal conference in New York City focused on improving and standardizing the American school bus. He brought together educators, transportation officials from 48 states, and bus manufacturers to collaborate on designing a safer, more modern school bus.

During this landmark meeting, the attendees proposed 44 national standards for the new school bus, including specifications for its size, doors, and aisle width. However, the standard that made Cyr famous was the introduction of 'school bus yellow.'

Why Was Yellow Selected for School Buses?

According to William Cyr, the son of Frank Cyr, his father aimed to find a school bus color that would be highly visible from afar and also stand out. 'So whenever we saw it, we'd think, there's a group of kids going someplace,' William explained in the same New York Times article. 'Before that, they sent kids to school in anything.'

In his office, Cyr spread out various color samples and instinctively gravitated toward a shade he referred to as 'orange,' a range of colors from orange-red to yellow and yellowish-green.

During the 1939 conference, Cyr displayed 50 paint swatches on the walls of the meeting room and selected a special committee to choose a final color. They ultimately selected the famous yellow-orange shade, initially called 'National School Bus Chrome.'

At the conclusion of the conference, Cyr published a 42-page booklet outlining the country's first school bus standards. And, of course, the cover of the booklet was painted school bus yellow.

Why Yellow Catches the Eye

Although Cyr wasn't formally trained in science or safety, he had an instinctual understanding of how bright colors enhance visibility and improve vehicle safety.

"Considering the standards from 1939, yellow was undoubtedly a smart selection," explains Dr. Stephen Solomon, a retired optometrist and founder of Visibility in Motion, a consultancy serving emergency service providers.

"The hues most easily detected by the human eye fall within the yellow range — from yellow-green to yellow to a greenish-yellow," says Solomon. "This spectrum is the peak for visibility, with no other color more attention-grabbing or noticeable than yellow."

The chart on the left illustrates how the eye's sensitivity varies across all visible light wavelengths, particularly during daylight hours.

Solomon explains that color perception is governed by photoreceptor cells in the retina known as cones. There are three types of cones, each specialized for detecting distinct light wavelengths: red, green, and blue. Yellow light activates both the red and green cones simultaneously, which is why the eye is particularly sensitive to yellow shades.

What Cyr likely overlooked is that 8 percent of men and 0.5 percent of women experience red-green color blindness, which makes it hard for them to distinguish between red and green. However, research cited by Solomon shows that golden yellow remains the "most visible color for both individuals with normal vision and those with color deficiencies, regardless of the testing conditions."

School Buses Are Built for Safety

Frank Cyr passed away in 1995, but he lived to see his vision of yellow school buses become a national standard and a true American symbol. According to the National Highway Traffic Safety Administration (NHTSA), every new school bus sold or leased in the U.S. must comply with federal safety regulations, including that iconic yellow paint.

While the bright yellow paint of school buses certainly makes them stand out, it’s the array of safety features that truly ensures their protection. The NHTSA rightfully labels school buses as "the most regulated vehicles on the road," with features such as high-crush standards, rollover protection, flashing red lights, and stop-sign arms all designed to safeguard passengers.

School buses are responsible for carrying millions of children each day. More than 26 million American children rely on 480,000 school buses to get to school. Thankfully, the NHTSA reports that less than 1% of all traffic fatalities involve children on a school bus. Between 2011 and 2020, there were only 113 fatalities on school buses, averaging 11 per year.

If school buses are so safe, then why don’t they all have seatbelts? One reason is that buses are large and heavy, which means they don’t stop as suddenly in a crash. Moreover, a safety concept called "compartmentalization" protects children by using closely spaced seats with energy-absorbing backs. However, buses under 10,000 pounds (4,535 kilograms) are required to have seatbelts.

If yellow is so visible, why are fire trucks still red?

Fire trucks have been traditionally painted red for over a century, though the origins of this custom remain unclear. From a safety standpoint, red is not the ideal color, as it is less visible during the day and nearly invisible at night, according to Solomon's findings.

Since the 1970s, some fire departments began adopting bright yellow trucks to improve visibility. This shift led to a significant reduction in accidents, proving the effectiveness of the color change.

In the 1990s, Solomon and a colleague conducted research comparing accident rates between red and yellow fire trucks. The results were stark: red fire trucks were involved in accidents at three times the rate of their yellow counterparts in Dallas, Texas, where both red and lime-yellow trucks were in service.

Despite the evidence, many fire departments remain reluctant to adopt yellow fire trucks. A 2009 report from the U.S. Fire Administration (a division of FEMA) confirmed that bright yellow and fluorescent colors were more visible than red, but it did not advocate for a universal switch to yellow vehicles.

"[I]t is a common belief that people are more likely to associate red with a fire truck than any other color, regardless of the circumstances," stated the USFA report, highlighting the traditional significance of the red color in easily recognizing emergency vehicles. Fire trucks also feature loud sirens to alert drivers, unlike school buses.