Eventually I became aware that I was hungry, so I started to pay attention to the billboards that I was passing now and then on the highway, to see which of them were indicating the imminent appearance of fast-food chains or hamburger franchises that would be near enough to the interstate that I wouldn’t feel as though I was going out of my way were I to follow an exit ramp and patronize one of them. Not that I was in a hurry to get to where I was going, or that I was trying to keep to a very strict schedule, but that I’d gone on these road trips often enough to know that I liked to maintain, as much as possible, the directional momentum that is unique to long-distance driving, and that is, perhaps, especially unique to long-distance driving across the United States.