Northwest Ordinance. An Ordinance for the Government of the Territory of the United States Northwest of the River Ohio. The Northwest Ordinance (officially the Ordinance of 1787) was enacted by the Congress of the Confederation of the States on July 13, 1787.orthwest Ordinance. An Ordinance for the Government of the Territory of the United States Northwest of the River Ohio. The Northwest Ordinance (officially the Ordinance of 1787) was enacted by the Congress of the Confederation of the States on July 13, 1787.