“Highway” means a lot of things depending on the context. Sometimes it’s an interstate system with on and off ramps, but it also refers to a non-residential road (though in western New York, I’ve seen houses with driveways that connect with I-84, so who the fuck knows what the deal there is).

For the purposes of stopping for buses/emergency vehicles, a divided highway is any nonresidential road with a raised median such that a car is unable to turn around at any given place. At least in my state.