This one:
It dissects the US along its cultural lines and traces them back to the original European settlements in the continent, and connecting the dots between the settlements and the cultural baggage, assumptions, and biases that those original settlers brought with them from their countries of origin (the English settlers of New England, Dutch settlers of New York, Quakers in Pennsylvania, etc) and follows them on their migration patterns as they begin to populate the West. Using that as the guideline he establishes multiple "nations", each with their own cultural, economic, and political profile.
He argues at some point that the cultural environment in each of these regions is shaped by the original settlers and people who come in later, unless they completely overwhelm and take over the region, find ways to fit into that mold. So in a lot of cases, the die is cast from the start.
The premise of the US (and Canada and Mexico) as a collection of nations is not a novel one, apparently, and there are other books who explored the same idea (Children of Albion is a name that comes up now and then, though not in the book) but what Colin Woodard does is to take this idea, expand on it, and lay it out in a language that is very very easy to read.
The content of this book may not be as revelatory to some people. And there may be some nits to pick, some oversimplifications to be argued over, but I think the basic premise is sound. So much that in the initial chapters as he's laying down the cultural make up of the people in one location and talk bout what they deeply care about, I was immediately connecting that feature to some aspect of modern politics, or cultural tensions we currently live.
There have been a handful of books I have felt so bullish about: Jared Diamond's "Guns, Germs, and Steel", Radley Balko's "Rise of the Warrior Cop", and then, this.
Highly highly recommended if you want to see this country in (what I consider to be) a more illuminating light and a more effective perspective.