I saw an old book from Yankee Magazine publishers at one of the bed-and-breakfasts we stayed at. It listed the best restaurants in New England. I quite naturally turned to the section on New Hampshire to see who they had favored in our fair state. It divided New Hampshire into two sections: Southern, and White Mountains. The boundary between them ran a little above Keene, Concord, Portsmouth.
Last year I claimed that the North Country began just about Concord at Exit 16. I took a fair bit of heat for that. Yankee Magazine was even more extreme than I was.