I'm largely in agreemebt, but I think it's a middle-sized area between local area and the size of a state. Once you have a slave revolt in a large area where blacks heavily outnumber whites, it's only a matter of time before you get a chain reaction where the majority of slaves in the area escape. If that's the case, you're getting slave rebellions of not tens, but tens of thousands. At that point, you need a professional army rather than just local militias to put it down. Even then, its questionable whether you can put the cork back in the bottle like Jamaica.
Let me try putting it another way. You didn't get significant slave revolts unless the conditions were so bad that slaves figured that they had nothing to lose,
and where they outnumbered the whites enough that they thought that they had a reasonable chance of winning.
The first was emphatically the case for most sugar plantations, particularly in the Caribbean. So, for that matter, was the second. Neither, however, was true in the antebellum South, and hence revolts were vanishingly rare there.
Again, this is what interviews with ex-slaves (and the historical record) make quite clear. It wasn't that slaves weren't willing to fight or run away, given the opportunity. They were, as the ACW shows. Given a realistic chance to escape (ie with Union armies close), slaves fled in droves. Given weapons and a meaningful opportunity to fight back, the former slaves fought for the Union.
What the slaves
weren't willing to do was die for no realistic chance of success. And they knew that this was the only realistic outcome if they revolted in the antebellum South.
In your example above, if it takes calling out the professional army to fight tens of thousands of slaves, yes, the South would do it. Without question. With "justice" administered through rifle bullets for the rebel slaves, and likely for any around them whose loyalty wasn't sure. And in such a revolt, "guilty" would mean "black and somewhere in or near the rebellious area".
The slaves knew this too, which was they they didn't rebel en masse in OTL. It wasn't that they were remotely fond of their condition, it was just that they preferred living to dying.
Yes, agreed. It won't be an instant thing, but as slavery goes on I would imagine those numbers would change to get up to those sort of numbers in some states (2/1 or 3/1).
No reason that it would. The birth rates and overall population growth rates for slaves and whites were pretty similar, and had been for a few generations.
I think the cities thing matters because the groups of slaves are closer together, so its easier for chain reactions to start. i.e. it's easier to stop a bunch of slaves marching to the next plantations than the next street. It's also easier for a conspiracy to be formed in advance.
I'm not sure I follow. The existing history of slave revolts (rare) and planned revolts (more common) showed that such things were easy enough to do in either rural or urban areas, including spreading from one plantation to the next (or one iron mill to the next - see the Tennessee slave conspiracy of 1856). In fact, given that in some rural areas, the slaves formed a massive majority of the population, I'd call it easier to spread revolt and conspiracies, since there were fewer whites around to keep an eye on the slaves.