There was a ritual to it. You'd pull out of the driveway before dawn, the car loaded with a cooler and a shoebox full of tapes. The 8-track player — or later, the cassette deck — was the most important piece of equipment in the vehicle. Not the engine. Not the map. The music.

The albums that worked best on the road shared certain qualities. They had momentum. They didn't ask too much of you. They understood that you were moving through space at speed, that the landscape was changing outside the window, and that the music needed to match that feeling of forward motion. Eagles' Hotel California. Jackson Browne's Running on Empty. Tom Petty's Damn the Torpedoes. Springsteen's The River.

The tape didn't skip. The road didn't end. For a few hours, everything was exactly where it was supposed to be.

Running on Empty deserves special mention. Recorded live on the road in 1977, it was literally made for this purpose. Browne understood something that few artists have captured before or since: that the road trip is its own emotional state, distinct from wherever you started and wherever you're going. The album sounds like motion. It sounds like America seen through a windshield at 70 miles an hour.

The 8-track had its limitations. The format divided albums into four programs, sometimes cutting songs mid-note to switch tracks. You'd be deep in a guitar solo and suddenly — click — you were in a different part of the album. It was maddening. And somehow, it was also perfect. The interruption reminded you that you were in a physical world, that music was a material thing, that the experience of listening was inseparable from the experience of being somewhere.

By 1979, the cassette had largely taken over. Smaller, more reliable, you could rewind. But the 8-track era left something behind: the idea that certain albums belonged to the road. That some music was made to be heard in motion, with the windows down and the miles stacking up behind you. That idea never went away.