The Breaking of Northwall (The Pelbar Cycle, #1)

One thousand years after a devastating and chaotic series of nuclear exchanges, all that is left of the United States of America are scattered, warring tribes and small city-states. One of the latter is Pelbar—proud, civilized, and intolerant of change and new ideas. Rebels and troublemakers are sentenced to a year of exile at the massive midwestern fortress of Northwall, defending Pelbar against the fierce Shumai and Sentani tribes. Restless and brilliant Jestak is a visionary who has seen and learned too much in his distant travels to be content with life in Pelbarigan. During his exile at Northwall, he makes contact with Pelbar’s age-old enemies and risks all to rescue his beloved Tia from nomads armed with long-lost weapons from before the atomic holocaust. Jestak’s daring quest for love brings profound changes to his world. 
The Breaking of Northwall is the first in a series of seven classic postapocalyptic novels about the Pelbar people. Williams’s fascinating and uniquely optimistic vision of an America long after a nuclear war has enthralled readers for decades.