#33 The Postman by David Brin
What to say about this. First, ignore the movie. Unlike many of the others, I did enjoy the movie, but it is not comparable to the book. I cannot believe that I had left this off my last list from a decade ago.
Welcome to your post apocalyptic future. Like so many other books, the world has fallen apart. Left in the middle of this mess is Gordon. He has wandered for years, trading what he can, salvaging, and staying away from the nut jobs. Like many of these moves, it is a Lord of the Flies situation. One group wants stuff, and the world will burn to get it, and the others want to work together to make the world better, and who will do a better job.
Gordon is ambushed, and runs off from all his stuff at a campfire. Upon return, the thieves had taken most of his stuff, and destroyed much that is left. While wandering in the cold mountain air, he ends up finding an old postal car. The driver long dead. He takes his clothes, boots and rummages the packages. Then he takes the letters to have something to pass the time. Apparently the post tried to keep going for a while after everything was falling apart.
Eventually he wanders into a town, and claims to be a post officer to get some supplies. The scam works when he has a few letters that he had taken for personal entertainment. The people are desperate for hope. He tells them he has permission to set up a postal stop, appoints a person as part of his scam, and they give him letters for the next town, and he moves on.
Slowly this small group grows. More and more put faith in him, and he starts to wonder if he should leave now or keep going. However, it is the faith of others, their hope, that push him further down that path. Eventually, he befriends a group of scientists that are keeping things going in Oregon, and joins forces with them.
However, in the hills are the crazy survivalists. They have gathered and run their own society and roll over everyone else. The strongest survive and prey on the weak, and this has gone on for decades. Now the postman uses his contacts and small lines of communication to organize the remains of loggers, ranchers and others from the disjointed corners of the state to come together to fight the threat.
There are many dystopian novels like this. I would say they are more common now, but they are not. They were as common in the 50s through 90s . They are just not thrown into the main stream as much. Now those have become the core of so many teen books/movies/shows. This is one that I return to read regularly.