Amtrak wars book 1 Cloud Warrior

I originally read this book in the early 1980's and recently decided to visit it again. Set in a post apocalyptic America hundreds of years after a devastating war, it focuses on the struggles between the descendants of those who took shelter in the government bunkers (the federation) and the descendants of those left on the surface (mutes). Mixing sci fi, fantasy and magic to create an engaging read, the series has run to 6 books so far.