Undivided roads
When a school bus stops with red lights flashing on a two-lane or four-lane undivided road, traffic in both directions must stop. Stay stopped until the red lights stop flashing or the bus moves, whichever happens first. The stop arm extending from the bus is a legal stop signal — treat it like a red light.
Divided highways
On a divided highway with a physical median or a median strip wider than five feet (rules vary by state), only traffic traveling in the same direction as the bus must stop. Oncoming traffic separated by the median can continue. When in doubt, stop.
Yellow versus red lights
Yellow flashing lights on a school bus mean the bus is preparing to stop. Slow down and prepare to stop yourself. Red flashing lights mean the bus is stopped and children are entering or exiting.
Penalties
Penalties for passing a stopped school bus illegally are severe in every state — typically a several-hundred-dollar fine for a first offense, with license suspension and possible jail time for repeat offenses or for incidents that result in injury.