A brief history of why the school bus is yellow, in this week’s New York Times:

The answer is Frank W. Cyr, a professor at Teachers College, Columbia University, who became known as the “father of the yellow school bus” for research he led in the 1930s.

Dr. Cyr, who died at 95 in 1995, had traveled the country, surveying pupil transportation in an era when school buses cost $2,000 apiece but differedwidely from manufacturer to manufacturer and jurisdiction to jurisdiction. Some states had safety standards; some left the task to local school districts. “In many cases, standards have been set up by more or less hit-and-miss methods,” according to an account that Dr. Cyr oversaw.

Then, in the spring of 1939, he called together educators, school bus manufacturers and paint experts for a conference that approved the nation’s first school bus safety standards — 42 pages covering everything from axles, batteries and emergency brakes to the inside height of the passenger compartment to, yes, the color that the world saw outside. The standards were published in a booklet with a yellow cover: the yellow was the color the group had chosen.

Nowadays, the color of the school bus is a standardized “national school bus yellow.”