Four hundred American citizens survived the nuclear war in a vast underground bunker beneath Houston, Texas.
Over time, their descendants established additional underground bunker-cities (known as divisional bases) linked by a high-speed subterranean rail network.
By AD 2989, when the novels begin, the Federation sprawls across much of the south of the United States, from Colorado and Arizona to Mississippi.
The Federation's personnel are heavily susceptible to above-ground radiation and rarely live past their fortieth birthdays as a result.
Ordinary citizens of the United States who managed to survive the nuclear war and adapt to the radiation mutated into a clan-based warrior society known as the Mutes.
Adopting a warrior ethos and tribal society similar to Native Americans, the Mutes are primitive, employing spears and knives in combat.
According to their legends, the Iron Masters fled the destruction of their homeland of Nippon in vast floating cities that drifted into Antarctic waters and then up into the Atlantic, eventually landing on the Eastern Seaboard of the former United States.
They founded a country known as the Shogunate of Ne-Issan, stretching from Nova Scotia to South Carolina and inland as far as the Great Lakes and Appalachian Mountains.
In AD 2989, a 17-year-old, newly qualified Amtrak pilot named Steve Brickman joins the Lady from Louisiana, a wagon-train in its first major assault on the Plainfolk Mutes.
Privately, Steve is recruited by the Federation's top-secret intelligence organisation, AMEXICO, and is sent on a new assignment to capture Cadillac, Clearwater, and Mr.
Other changes include proposed variations to the design of Federation vehicles and technology from the books, and the removal of Ne-Issan to the Pacific Northwest rather than the Eastern Seaboard.