[Sherman Logan]

It wasn’t “the” factor – slavery was on its way out anyway, and given 5 years or so, would likely have been entirely dead on its own.

That is, of course, why the slaveowners kept bidding up the price of slaves, reaching a record in 1860. Because of course intelligent investors always sink their money into investments they know will be worthless in five years.

[Reily]

Brazil kept slavery until I think the mid-1880s.
Eventually it would have been done away with due to economic inefficiency. Slavery was holding the South back economically. The moral dimension also would force its extinction. I doubt if it would have survived until 1900.

I read somewhere that there was a letter in the Vatican archives from Jefferson Davis where he acknowledged that slavery was on its way out and that he would certainly trade it for Southern independence.