In the 21st century, a meteor hit somewhere. Nobody knows where, but it hardly matters anymore. What does matter is, food supplies fell short, a war broke out, and all the governments fell apart, one by one. It is now a thousand years after that.
The dust kicked up by the meteor interfered with communications, and the governments all destroyed each others' sattelites. If any are left, they don't work. The good news is, no nuclear weapons were used for fear of food contamination.
In the aftermath, many people resorted to piracy; It is estimated that there are hundreds of thousands of pirates on the roads and seas, stealing any food they come across. As a result, most islands in the sea became disconnected from the outside world. Thousands of small republics, minreps, formed everywhere. Many of them formed alliances with other minreps and effectively act as a single nation. Euskadi, Basque Country, in former Spain, is an example of this.
Most big cities fell to gang warfare, and were divided into urban territories. Eventually, the violence faded, and the inhabitants put dirt on the rooftops to grow crops and combat hunger.
Small farming communities lost touch completely, and survive on their own.
The protagonist is a Roader. He currently is in southwest Nebraska. He travels from town to town buying and selling things from other towns. He travels the roads in his car, which is in terrible shape but works well. It was altered to run on alcohol, since all the oil was used up decades ago. At the moment he travels alone, convoys of cars are easier to defend but pirates spot them more easily as well. All rodsters keep a constant vigil for the Road Pirates. They travel in packs of cars, each with their clan symbol painted on it, and they are bloodthirsty predators.
Rod finished filling his tank with alcohol and started up the engine of his old car. Strange, how cars could now run on the stuff people used to get drunk on. Still, a much more useful purpose. He checked again his cargo hold, the people of the Colorado Union relied on him and other roaders to survive, transporting food and other supplies from the isolated farming communities of the central fields to the few urban centers. Last, but not least, he checked his J. P. Yuan 177 submachine gun with a H-21 custom mounted grenade launcher, if he ran into any of Colorado pirates on his way, that would be the only thing able to save him from their barbaric anthropophagous torture rituals, either by shooting them, or himself.
After the checklist was done he entered into his Ford DuneRider 2067 and bid a silent farewell to Farmington, with a new supply of alcohol bottles. At first, most of the alcohol he got was distilled from alcoholic beverages, but now...well, one of the good things of the greenhouse effect, Rod supposed, is that sugar cane could be easily produced almost anywhere in the world, which ended with the latin american monopoly of high quality alcohol-based combustibles...not that this could, in any way, make up for the bayou that dominated most of the litoral now, and the hellish heat waves, but at least it wasn't all bad.