Nope, completely my mistake. What threw me was the northwestern border which follows some river (I don't have an atlas in front of me) encompassing OTL southern Indiana and Ohio. The dip down looked like the WVA was there and the missing portion of the Virginia panhandle contributed to that.
Just the Wabash.....I believe the map takes a detour up the Wabash (?) and down the Whitewater (?).
One of the maps I used as a basis........This map might be helpful to the discussion:
I modified the map, with NY joining the PA nation instead of NE.......