"John would have been 18 and Rebecca 16."
John,
I agree with that conclusion. 18 & 16 would be about the right age considering the time. The area that we find John in is actually a very small part of the state and I can visualize people moving around that area quite easily. Probably the whole of the area would be a matter of a few hundred square miles. A common thread for me is the Illinois RIver. A good source of supply for the residents both in terms of recieving supplies and selling surplus crops and animals, etc.
Frank