As a child, I thought highways were called highways because they often ran on overpasses or on elevated levees. But this isn’t the case over most of the country they run through. They are ground level roads.

So, what’s ‘high’ about them? We hear of Highways and Byways, but there are no roads called Byways. Maybe we say Hi when arriving on a highway and Bye when leaving on a byway, but again, no roads are called byway.

And the rest of the question, why are parkways for driving and driveways for parking?