As the 21st century progresses and we se our country increasingly fragmented, this book has new relevance. It's all about how the U.S. is actually a collection of interrelated "nations," each one capable of functioning on its own. I first read this back in the 70s, and was so taken with it that I wrote a short review of it for Stuart Brand's Whole Earth Review. If you write speculative fiction, this book will spark a lot of ideas for near-future settings.