It may be different in Europe, but according to Wikipedia, the term highway in the U.S. designates a major road, such as a controlled access highway where one might expect to see a sign like this: It would be pretty unusual to see a cyclist on the side of a large highway; more often you will see someone walking, but even then it is usually because their car has broken down. But outside of urban areas, bike lanes are not common and cyclists share space with cars. If I had to do that, I would think more about wearing a helmet, but I would probably just drive.
Just chiming in to say that many of the major bike routes in Austin -- for the people who like to knock 20 miles before work or what have you -- include what I would consider long stretches of highway. It's in-between highway, the ones where you can hit 60 but intermittently have to stop for red lights. In any case I don't wear helmets because I absolutely hate them.
I feel like I have to piggy-back off of every Austin comment you make but I bike a lot in Austin and there is no way to bike on the highway unless you either like being honked at or like riding the shoulder. Even in the city it's uncomfortable in most places unless they separate the bike lane from the road (like on Guadelupe with the potted plants), but even then, cars take turns without considering bicyclists. Despite the discomfort, I make most of my trips on bike mostly due to a lack of motor vehicle. I do ride defensively to avoid any misunderstanding with cars, but problems still happen. Today even, I was riding in the rain and I had to slide a solid ten feet to my left with my leg out in order to take a right turn without being rear-ended by a car tail-gating. I wouldn't have been worried about this in my car but then again I don't own it anymore. I never wear a helmet either, but I'm also wearing a wrist brace because of an accident involving a a car and the driving and road conditions here.
I was clearly talking about the shoulder of the highway. You see them every day on 360, etc. To be fair, this is based on the assumption veen's ridge is the same as America's shoulder.I'd never use a bike helmet here in the Netherlands, but if I were to drive on the ridge of a highway (illegal here, but a common sight in America I think)
Sorry flag, when I said "there is no way to bike on the highway", I wasn't trying to dismiss your comment about the ability to bike on those stretches of highway. I was trying to say that it wasn't a comfortable place to ride but I can see how that part of my comment could have been taken.