Oy-vey, you always ask the questions which make me strain my brain
Ok, here is my answer. As we all know, the Articles of Confederation was a failure. It was pretty much predicated on states rights. without a strong Federal government, taxes could not be levied, armies could not be raised, National Banks could not be formed, etc.
So they founding fathers got together and hammered out the Constitution (for interesting reading leading up to the ratification of the constiution, read the Federalist papers). There was a lot of angst going on here though because in the new representational form of government proposed, the north would have the ability to outvote the south on any regionally divisive issue since the representatives for each state were based on population counts. Therefore a compromise of sorts was reached which provided for each slave to be counted as 3/5ths of a person for purposes of representation.
Consequently the need for slavery to be spread as states were created was paramount so that the south could have a chance in voting down legislation that did not favor them. That plus the fact that the founding fathers did not outlaw slavery period in the constitution would lead to all the failed compromises, the fugitive slave Law, the Dred Scott decision all paved a road toward disunion.
I may be wrong but I believe if the founding fathers had found a way to abolish slavery at the onset of the Constitution, there would not have been a Civil War. I know there are probably a lot of people on this board who may think that states rights was the paramount reason for the war, however, if you think about it logically, almost every thing you can bring up including the Morrell Tariff which was passed after secession has slavery mixed up in it and therefore was a reason for the war.
Bill