What is the setting of Swan Song by Robert McCammon?

The novel spans a time period of seven or eight years. It encompasses many different geographic locations within the post-apocalyptic United States of America. Sister's story begins in Manhattan, but she journeys out of the destroyed city through New Jersey and Pennsylvania to discover the town of Homewood. She and Paul go to Matheson, Kansas, where they discover Swan's tarot card. They spend many years wandering around the country before arriving at Mary's Rest in Missouri with the other characters. Swan and Josh meet at PawPaw's grocery store in Kansas, from which they journey out and into Nebraska. After adding Rusty to their entourage, they head for Mary's Rest also. Roland and Macklin meet on Blue Dome Mountain in the collapsed Earth House. They move out from the wreckage of the mountain to the Great Salt Lake, eventually forming an army that marches all over the north.