In your opinion, what was the most important element of the Northwest Ordinance of 1787? Why?

One of the most important elements of the Northwest Ordinance of 1787 was that the Federal government would be sovereign and would expand westwards in hope of founding new states, instead of expanding existing states. This was important for the growth and expansion of the United States (had this not happened, the United States would not be half of what it is now). Another important aspect of the Northwest Ordinance of 1787 is that slavery was prohibited and this was basically the border between free and slave states.