COLUMBUS, Ohio (WCMH) – The yellow school bus plays an iconic role in the back-to-school season, but the bright hue is more than tradition.

Every day, 26 million students in the U.S. use school transportation, making it the country’s largest public transit system. The majority of school buses are a distinct bright yellow, a color chosen to enhance safety and recognition for student passengers.

Frank Cyr, a professor at Columbia University, is known as the “Father of the Yellow School Bus,” though he always thought the color was more orange than yellow. Cyr organized a national safety conference, gathering school bus manufacturers and transportation officials from 48 states. This conference led to the establishment of national school bus standards, including the decision to paint all buses yellow.

The color officially called “National School Bus Glossy Yellow,” was selected from 50 swatches displayed on a wall. At Columbia University, where the conference occurred, the bright yellow was chosen for its ability to show black text clearly in low-light conditions, such as early mornings when buses pick up students.

Cyr organized the conference and the creation of the first national school bus standards after researching school transportation. He discovered disparities such as a Kansas district using horse-drawn wheat wagons for student transport and another district painting its buses red, white, and blue for patriotic reasons. Cyr was troubled by the inconsistency and its potential impact on safety.

While many of the 44 school bus standards established at Cyr’s conference have evolved, the color remains unchanged. The bright yellow color is acknowledged for enhancing student safety; according to the National Highway Traffic Safety Administration, less than 1% of traffic fatalities involve students on school buses, thanks to safety measures including the yellow color of school buses.

Although there are no national mandates requiring school buses to be yellow, it is advised. In states like Ohio, buses must be yellow, and a bus can even fail a state inspection if it does not meet the color requirement.

Experts say that over millions of years of evolution, humans gained the ability to quickly identify yellow, making them one of the only mammals to develop a third color-processing cone in the eye. According to one study, primates likely developed the ability to see more colors than many other mammals in order to more easily identify ripe, yellow fruit against green foliage.

According to Iowa State University, the human eye is most sensitive to a yellow-green color. At night or in low lighting, eyes process colors differently, but still favor yellow and some green shades. This makes School Bus Glossy Yellow especially visible, even from the periphery, helping ensure drivers are cognizant of student transportation.

As students return to school, transportation safety organizations encourage drivers to remind themselves of bus safety laws and to always look out for the bright yellow bus.