The Road by Cormac McCarthy

The Road is a 2006 novel by American writer Cormac McCarthy. The Road is a post-apocalyptic tale of a journey taken by a father and his young son over a period of several months, across a landscape blasted by an unnamed cataclysm that destroyed all civilization and, apparently, almost all life on earth. The novel The Road was awarded the 2007 Pulitzer Prize for Fiction and the James Tait Black Memorial Prize for Fiction in 2006.
The Road follows an unnamed father and son journeying together across a grim post-apocalyptic landscape, some years after a great, unexplained cataclysm has destroyed civilization and almost all life on Earth. Realizing that they will not survive another winter in their unspecified original location, the father leads the boy south, through a desolate American landscape: along a vacant highway, towards the sea, sustained only by the vague hope of finding warmth and more "good guys" like them, and carrying with them only what is on their backs and what will fit into a damaged supermarket cart.
The setting is very cold, dark and filled with ash and the land is devoid of living vegetation. There is frequent rain or snow, and electrical storms are common. Many of the remaining human survivors are cannibalistic tribes or nomads, scavenging the detritus of city and country alike for human flesh, though that too is almost entirely depleted.
Overwhelmed by this desperate and apparently hopeless situation, the boy's mother, pregnant with him at the time of the cataclysm, commits suicide some time before the story begins; the rationality and calmness of her act being her last "great gift" to the man and the boy. (Summary by Wikipedia)