Indeed, people outside the US (especially Europeans) don't really grasp the scale of the US interstate highway system. To paraphrase Douglas Adams, "The United States is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."

It's so big, that if you're driving long distances over the middle of the country you have to make sure you stop for fuel and food and a biology break whenever you get the chance, because there's no guarantee you're going to be able to find a place in flyover country.