I understand the aberration argument, and clearly Manhatten and D.C. are unique entities. What I would say is that there is no law that there be only 9 nations. Perhaps there were only 9 nations twenty years ago, but I would say that the foundry nation has probably split. No doubt the rust belt once ran from the upper midwest to atlantic seaboard, but I would say that the east coast cities have been able to shed that legacy better than their mid-west counterparts.
I would also say that the Dixie nation has split as well into the old south and the new south. The old south would mostly be SEC states, while the new south would mostly be ACC states (yes I know there is overlap and the outliner of Boston College).