The yellow school bus looks the same almost everywhere in the U.S.—big, boxy, and unmistakably yellow, with bold black stripes and a swinging stop sign.

It’s been this way since 1939, when a group of educators and engineers met to standardize school transportation. Before that, kids got to school however they could—by farm wagon, truck, or even horse cart. They chose “National School Bus Glossy Yellow” because it’s one of the easiest colors to spot in early morning light, even out of the corner of your eye.

Most public school students can ride the bus for free if they live far enough from school—usually more than a mile. Routes are tightly mapped out, with set stops on neighborhood corners or, in rural areas, right at the student’s home. It’s a massive, coordinated effort that moves millions of kids every day—quietly and reliably, five days a week.

And for me, it still looks so distinctly American— like something out of a movie—that I can’t help but stop and stare whenever I see one go by.