In order to form a more perfect union, the thirteen States of the confederation, assembled together for a Constitutional convention that ultimately resulted in a written Constitution, ratified by the States in 1788. At the time of ratification, all those States that still permitted slavery within their borders were allowed to maintain the institution of slavery; however, the Constitution addressed slavery in a manner in which, the importation of slaves, as of 1788, (which at that time importation was only permitted in the States of South Carolina, North Carolina, and Georgia,) was subject to being banned in 1808; and in fact, on January 1, 1808, President Jefferson signed into law, the banning of the importation of any slaves into America. This meant, that from January 1, 1808, slavery in order to sustain itself within America would have to re-populate itself from those that were already enslaved within America, and further that slavery, was only permitted in those States that allowed that peculiar institution.
Based on the fact, that the importation of slaves was eliminated in 1808, along with the fact that the northern States had proven that slavery was not an institution that was necessary for economic growth; it was felt, by many esteemed personages, that slavery as an institution, would over a period of time, simply fade away and dissolve. Obviously, that did not happen, and further to the point, when America acquired additional land, beginning with the Northwest Ordinance of 1784, Thomas Jefferson proposed on the draft of that Ordinance that "after the year 1800 of the Christian era, there shall be neither slavery nor involuntary servitude in any of the said States...", of which this was rejected and thereby removed from that Ordinance. Therein, this meant that the peculiar problem was not resolved in 1784 for future States, nor was this addressed at the Constitution Convention; for America, which began as a union of thirteen States, expanded into additional States, from territories acquired, in which, the southern States, were absolutely united, in recognizing that they needed to maintain enough veto power in the Senate, to protect their peculiar institution, so that new States admitted to the Union were admitted in a manner that for each free State admitted there would be a corresponding slave State admitted; all done, despite the fact, that western nations which had been previously intimately involved with slavery, the slave trade, and the importation of slaves, had reverse course, in the recognition that slavery as an institution had no place among progressive nations and was thereby an affront upon humanity.
The problem that America had with slavery, was not contained within the Constitution, for those that wrote and ratified the Constitution, were well aware of the institution of slavery, of which, the belief of those of the north, was that time and justice was on their side, and that if the fuel of new slave importations was banned, which it was in due time, than slavery would eventually flame out, which it did not. What the provisions of the Constitution did not do, was set in stone, the conditions that territories which became new States would have to adhere to in regards to the institution of slavery, in which, because certain new territories thereby permitted slavery, those that had a vested interest in slavery, were able to readily stoke the fires of slavery, to the point, that the ensuing conflagration was inevitable and those burning fires, still smolder until this very day.