In April 1939, a conference of transportation engineers, bus manufacturers and paint companies at Columbia University's Teachers College set up 44 national standards for school buses, including color, length, ceiling height and aisle width. Most have changed, but the standard yellow, called "National School Bus Glossy Yellow," remains in use nationwide. It was chosen because black letters are easy to see against the yellow background.

The color was adopted by the National Bureau of Standards (now the National Institute of Standards and Technology) as Federal Standard No.  595a, Color 13432. No federal law requires school buses to be yellow, but all states have adopted the standard, which is part of the U.S. highway-safety-program guidelines.

Published Friday, Sep. 22, 2006