I've had this conversation before... Oh yeah! With Papa Prog Smurf....
There would have been no union. We would not have become the United States because the southern slave states refused to sign onto the union if the northern states attempted to abolish slavery. But you know all this, you're just using the same talking points the looney left here in the states use.... looking for any reason to denigrate the United States, and its Constitution, as flawed from our nations founding and in need of being completely remade.
A point of order if I may, and if you would feel more comfortable discussing this in another thread, by all means start it and I will be more than happy to discuss it with you.
It wasn't that "the southern slave states refused to sign onto the union", it was because Georgia and South Carolina refused due to the severe economic ramifications if they did, and with Spanish Florida laying just to the south of them, the prospect of them becomeing part of the Spanish territories was unacceptable, especially with British controlled Canada to the north, and the French controlled Louisiana territory to our west, which is why the 3/5ths compromise was included in the Constitution.
Contrary to what some of us were taught in our government schools, the 3/5ths compromise was not emplaced because blacks were considered only 3/5ths of a person, but in response to Georgia and South Carolina refusing to go along with the abolishment of slavery, so it was decided that they would only be
allowed to count slaves at 3/5ths toward their census for representation in Congress, in order to 'punish' them for their stiffnecked refusal to abolish slavery. If they wanted to be allowed to fully count the black population of their states towards their census for representation in Congress, they would have to free them. The other southern states, and in particular North Carolina and Virginia were more than willing to abolish slavery, and in fact Thomas Jefferson had worked the vast majority of his adult life towards that very end.
The original 'plan' proposed by Jefferson and others was that the slaves were to be freed, the plantation owners would be compensated out of the federal treasury (5th Amendment compensation), and the former slaves were to be likewise compensated and repatriated to Africa, which eventually happened, after a fashion, with our purchase and establishment of Liberia for former slaves.
Of course, this is merely a very quick gloss, and bears far more discussion by those who are interested in honestly discussing their history, so as I said earlier, another thread would probably be the best place for such a discussion.