Easy Rider, Badlands, Thelma & Louise—the list of American road movies is long and winding. But the very best of the lot also happens to be the least iconic. It didn’t explain the mood of a generation and demurred on delivering a manifesto.

But if no eras were defined in the making of Two-Lane Blacktop, which turned 50 in July, that’s because Monte Hellman’s existential 1971 film about drag racing transcended its era, even if it stalled at the box office.