July 13, 1787 the Congress of the United States,  this is the government under the Articles of Confederation, passed the Northwest Ordinance.  This is one of the best acts of the government we had before the Constitution.

Under the Northwest Ordinance, Congress set out how to divide the territories into townships, and set up the organized settlement of Ohio, Illinois, Indiana.

But the best thing that this law did was to prohibit slavery in those territories.  The later disputes over moving slavery into new territories applied to the land we got under the Louisiana Purchase and the Mexican War.