The title refers to the path the man and the boy follow as they make their way down from the mountains towards the southern coast. The novel is set in the Appalachians, where McCarthy grew up. Like the people, the mountains are not named, but there are enough geographical clues that we can identify them.
McCarthy describes the setting in whites and grays and blacks. The world is leached of color. The trees and other vegetation have died, and forest fires have swept through the mountains. The higher reaches of the mountains are still burning, but most of the rest of the world burned up long before the present time of the novel, and all that is left is ash, everywhere. This is a novel of ashes, shadows, darkness. The boy and the man wear masks to protect themselves from the ash. McCarthy has always been a master landscape artist. His abilities are especially evident in The Road, but here the landscape is desolation.
Wrack and ruin characterize The Road. We are constantly reminded of the lost human world. Empty houses, sheds, barns, cars, trains, stores, where humans once dwelled. They are vacant now, empty, except for occasional mummified corpses. Garbage, junk, all the lost possessions of the human race litter the pages of this novel. It is haunted by the constant memory of what was there before, the world before the apocalypse. The shell of that world is still partially there, empty houses and stores and other structures. Highways, bridges, railroad tracks are all still there and may still be there, as the man explains to the boy, for thousands of years to come. But the human world, the world that created those objects, is wholly gone.
The man spends a lot of time rummaging through vacant houses, looking for cans of food, anything that he and his boy can eat, but the finds are rare. Once he comes across an old soda machine he scavenges an unopened Coke that he gives to the boy, who has never had a Coke, and who will never have one again. The novel is a story of constant starvation, and the man and the boy are on the verge of death from starvation more than once, only to run across an unexpected cache of food, once in a fallout shelter, on another occasion in a beached boat.