What was the greatest influence in the northwest ordinance of 1787?

Well, it was an act of the Congress of Confederation in the U.S, and it was a very important piece of legislation passed by the Confederation Congress. That's all I know, sorry if not enough. 

Influences to the Northwest Ordinance were the pressure to expand westward, the diplomatic tension between Great Britain and Spain, conflicts with the Native Americans, a weak governing document (The Articles of Confederation), and a need to improve the country's bullion, for the American treasury was having issues during this time period.

From mexican american war , us gained new mexico.