Final answer:
The Northwest Ordinance established the methods for territory division and statehood admission. It banned slavery in the Northwest Territory which set an anti-slavery precedent that influenced the creation of the Republican Party
Step-by-step explanation:
The Northwest Ordinance didn't form the basis of a specific American party, but it did establish important principles and precedents that influenced subsequent American politics. Notably, the Northwest Ordinance of 1787 enacted territorial boundaries, governance principles, and conditions for admission of new states into the Union. It forbade slavery in the new territories, which set a precedent and fueled the debates that ultimately led to the Civil War. These debates resulted in the formation of the anti-slavery Republican Party.
Particularly, the Northwest Ordinance established a territory which eventually became the states of Ohio, Indiana, Illinois, Michigan, and Wisconsin. It facilitated the orderly method for the admission of new states, and provided a roadmap for future territorial evolution and statehood. Significantly, it outright banned slavery north of the Ohio River, which played a substantial role in the political discourse regarding slavery and its expansion, sustaining a portion of the ideological groundwork for the advent of the Republican Party in 1854.
This political party strongly opposed slavery spread to the West. Bearing that, the Northwest Ordinance and its abolitionist stance undeniably had significant implications on the country's political landscape and future party formations, though it wasn't directly connected with the formation of a specific party.
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