What is the official name of the yellow paint used on US school buses?

The official name of the yellow paint used on U.S. school buses is National School Bus Glossy Yellow.

The color was standardized in 1939 at a national conference organized by Frank W. Cyr, a rural-education specialist at Teachers College, Columbia University. Representatives from all 48 states at the time, bus manufacturers, and paint companies worked toward common school-bus design and safety standards. The distinctive yellow-orange shade was selected because black lettering stood out clearly against it, especially in the dim light of early morning and late afternoon.

The color was originally called National School Bus Chrome, referring to the chrome-yellow pigment used at the time. Because the original lead-chromate pigment was toxic, manufacturers later changed the formulation. The official name consequently became National School Bus Glossy Yellow.

The color is strongly associated with North American school buses, but it is not a universal worldwide requirement. In the United States, federal authorities recommend the standard shade, while detailed requirements can also depend on state rules.