A slave must've lived in sight of the "free zone" (evidence: http://www.slate.com/blogs/the_vault/2013/09/04/abraham_lincoln_the_president_used_this_map_to_see_where_slavery_was_strongest.html the northernmost slave county on the continent was under 0.1 or 0.05% slaves but not zero and was under 3-4 miles from Ohio or PA everywhere in the county) Since there were so many slaves if I had to guess I would guess that some probably lived on a farm bordering a free state or territory (though yes they were not completely safe until Canada)
Did any live or work on islands in the rivers between slave and free that belonged to the slave side? Or even on one of those weird lands that happen when a channel silts up and moves a piece of your state to the wrong side of the river? That must be the most isolated you can be from the slave states while still in a slave state. Not only is there a land border but there's a moat between you and all but like 3 southerners.
What effects of closeness to the north do historians know about?
I also wonder what causes a guy to decide to have slaves that plow inches or yards or whatever the minimum was from the Mason-Dixon line or be the northernmost dude with slaves in a surrounded sliver of the side of the state that's relatively anti-slavery, and with a land border (Hancock County, WV).
@commenters: Yes, I know they were still "property" in the free states that allowed them there temporarily but I assumed they wouldn't allow you to farm with them in the free states. I just guessed that some would use their "property" as a servant while they were traveling through free states as it's indoors so who could find out. If they even had laws that they couldn't work in transit, that is. Did they even have laws that you couldn't make the slave work but you could still bring them in for awhile? If they were that anti-slavery then why wouldn't they just pass a law like my state (NY) which didn't allow them in without freeing them?