The speaker begins by listing memories, and nearly all of them involve machines: a car's headlights sliding across a bedroom wall, a plane buzzing overhead, motorboats on lakes, long drives to school, orange buses, even old ironing machines. These images feel warm and a little wistful, and the speaker admits, "I was happy."
Then comes a doubt. Are machines really romantic? The speaker confesses a wish for them to vanish, so the earth could stay unpaved, rough-smelling and quiet. Cars are called "murderers of silence," which is a sharp, angry phrase.
The ending softens that anger. Machines and nature turn out to be tangled together in the speaker's longings, "merged and mellowed." Steel, hard as it is, "softens in nostalgia." The mood is reflective and gently conflicted. The speaker can't cleanly reject what she criticizes, because it is bound up with the happiest parts of remembering.