There used to be no rules for school transportation.
Kids went to school in horse-drawn wagons and some districts had red white and blue buses, to instill patriotism.
That changed with this guy: Frank Cyr.
He was a professor at Teachers College at Columbia University.
In 1939 he put together a conference focused on the school bus.
He brought together teachers and transportation experts, engineers and, yes — paint specialists.
They came up with 42 pages worth of school bus regulations, among them: a yellow hue.
They decided on yellow because black letters were the easiest to see with a yellow background, and yellow stood out even in bad weather.
In fact, the color is now officially known as "national school bus glossy yellow."
Federal law does not require all school buses to follow this practice, but the National Highway Traffic Safety Administration does list it among its recommendations.
Every day, 480,000 school buses drive kids to school across the U.S.
They go in different directions, and drop off at different schools, but you can always count on that yellow color being the same.