What was the role of the northwest ordinance and what was its effect on the banning of slavery?

http://en.wikipedia.org/wiki/Northwest_Ordinance

The Northwest Ordinance was an important law passed by the United States Congress in 1787. Its role was to establish a method for admitting new states into the Union and to regulate the settlement and governance of the Northwest Territory, which encompassed lands north of the Ohio River and west of the Appalachian Mountains.

In terms of the banning of slavery, the Northwest Ordinance played a significant role. It explicitly stated that "there shall be neither slavery nor involuntary servitude" in the Northwest Territory. This prohibition on slavery was groundbreaking, as it marked one of the first times a U.S. law explicitly addressed the issue of slavery.

The impact of the Northwest Ordinance in terms of banning slavery was twofold. Firstly, it provided a legal foundation for the exclusion of slavery from new states that would eventually be carved out of the Northwest Territory. Secondly, it set a precedent that influenced future laws and debates on the issue of slavery, particularly in the context of the western expansion of the United States.

The language of the Northwest Ordinance's prohibition on slavery was later incorporated in the constitution of states such as Ohio, Indiana, Illinois, Michigan, and Wisconsin, which emerged from the Northwest Territory. These states, often referred to as "free states," did not allow the institution of slavery within their borders.

It is important to note that while the Northwest Ordinance banned slavery in the Northwest Territory, it did not abolish slavery in already existing states nor did it address the issue of slavery in other parts of the country.