Woodard openly credits Garreau's work as one of the foundations of his own book, so he would say American Nations represents a refinement or update of the same principles.

I have read Woodard but not Garreau. Woodard's book is extensively endnoted but I cannot say I've researched any of his sources. But while his sources speak to a kind of historicity, it seems to me that Woodard favored instances that supports his thesis, and didn't really account for other factors (effects of urbanization, socio-economic classes) that undermine his pat generalizations. That said, I still found it to be an interesting read and good food for thought.

Apropos of nothing: he does not mince words when it comes to the Deep South.