The Henderson family's plan for an island retreat takes an unusual turn when they discover the island they have just purchased in the St. Lawrence River is an independent country. Another story about the family from Why Not Join the Giraffes?
I read this young adult book 30 years ago & remembered the delightful premise, but not the title. Finally discovered the title and author and ordered it via Interlibrary Loan. The book came from the Enoch Pratt library, Baltimore's library system, perhaps the identical volume that I read all those years ago. The hippie slang and peace movement plot are dated, but it's still a fantastic premise and a heap of fun.
Loved this book! I read it in 1974, I believe, and the story has stuck with me ever since. In fact the summer I read this novel I also read The New Adventures of the Mad Scientists Club which featured a clubhouse/cave behind a waterfall. I'm convinced the 2 books were indications of my overall desire to escape.