The Heir series by Cinda Chima
Book 1 qualifies as Ohio for my USA by the book challenge. Book 2 is more than 50% set in Maine, so I'm counting it as fulfilling that state.
This series was a re-read for me. It is more urban fantasy, less high fantasy, with a Harry Potter'esque (wizards among us) conceit. There is a completed story for each book, as well as a satisfying three book narrative arc that concludes at the end of The Dragon Heir.
I do not love these quite so much as I love Chima's other series - The Seven Realms - which is more high fantasy and less urban fantasy. Overall, though, I read these three in about as many days and enjoyed them a lot.
There is now a fourth book, The Enchanter Heir, which I am reading right now. It feels sort of tacked on, and introduces some additional world building. I am on the fence as to how successful it is at this point.