Delaware, Maryland and Missouri go during the 1860s. With the new Senate makeup, slavery is banned in DC, and possibly a defanged fugitive slave law. Kentucky and Tennesee in the 1870s, Virginia and possibly Arkansas in the 1880s. But Virginia is a different place than the states which went free previous; there's no way uncompensated manumission is getting through the state legislature, so all those planters will have to be payed from state funds. It'll break the state for at least a generation.
By this point, agricultural slavery has ceased to be profitable. The political tide has turned quite against slavery. I don't think the South will make a leap to some sort of industrial slavery (although obviously you can find other opinions on this board), but Virginia's example means they aren't willing to pay for it. So the remaining 8 or 9 slave states try to extort money for manumission from the Federal government - but being rid of that institution is likely to make the North happy enough they may go for it.