It struck me that there were several cases of states voluntarily giving up territory, on the grounds that it was impossible to control from the state capital due to geography and therefore would be better handled by a neighbouring jurisdiction - this is the explanation given for Washington shedding the gold fields which became part of Idaho, and for the trimming of the town of Boston Corner from Massachusetts to New York. That's rather different from the approach to territoriality I am used to elsewhere - it speaks to a trust that neighbouring jurisdictions could handle one's own troublesome citizens better. Armed conflict over territorial aggrandisement was very rare, the 1836 Toledo War between Ohio and Michigan being the most recent example.
Though I do wonder if it's true if, as reported here, those of the original colonies with claims west of the Appalachians surrendered them to the new federal government fairly smoothly, apart from the westernmost bits of Virginia and Connecticut's Western Reserve (now in Ohio). I also wished Stein had gone into more detail on the secession of Vermont from New York and of West Virginia from Virginia - I know that he left out some interesting details from the latter and I had hoped to learn more than I did about the former.
Since Stein covers all fifty states, and the Dictrict of Columbia, in alphabetical rather than historical sequence, there is a fair bit of repetition (the Watkins Point story is told in the chapters on Virginia, Maryland and also Delaware). But it's all lucidly done and nicely illustrated with clear maps.
Maybe someone should do a book like this on the borders of European countries. I have sometimes asserted that most of them were formed as tide marks in the ebb and flow of empires; maybe that proposition can be proved one way or the other.