Thanks to Crayshen 's comment I went in to double check. Yes, the border counts.
So if I am in the Bottom Right of Silverpine, my position is [48,-49], and when I pass through the border 1 step to the right, being at the very bottom left of the map section to the right of Silverpine, my position is now [51,-49].
I will now go to the second area right of Silverpine to see if my position will end up being [101,-49] or something else.