What did they ban in the northwest ordinance?
They banned slavery form the northwest ordinance.
Why is the northwest ordinance of 1787 considered to be the outstanding achievement of congress under the articles of confederation?
Thomas Jefferson wrote the Ordinance of 1784 which was significantly different from the Ordinance of 1787(A.K.A. the Northwest Ordinance). although most of the ideas from the Ordinance of 1784 were carried over into the revised document, Thomas Jefferson was not involved in writing the Ordinance of 1787 except for leaving behind a framework for others to use.