The Northwest Ordinance (formally An Ordinance for the Government of the Territory of the United States, North-West of the River Ohio, and also known as the Freedom Ordinance or The Ordinance of 1787) was an act of the Congress of the Confederation of the United States (the Confederation Congress), passed July 13, 1787. The ordinance created the Northwest Territory, the first organized territory of the United States, from lands beyond the Appalachian Mountains, between British Canada and the Great Lakes to the north and the Ohio River to the south. The upper Mississippi River formed the Territory's western boundary. It was the response to multiple pressures: the westward expansion of American settlers, tense diplomatic relations with Great Britain and Spain, violent confrontations with Indians, the weaknesses of the Articles of Confederation, and the empty treasury of the American government. It was based upon but more conservative than Thomas Jefferson's proposed ordinance of 1784. The 1787 law relied on a strong central government, which was assured under the new Constitution that took effect in 1789. In August, 1789, it was replaced by the Northwest Ordinance of 1789, in which the new Congress reaffirmed the Ordinance with slight modifications.