Passed by Congress in July 1787, the Northwest Ordinance laid out the basic form of government for all western territories later to be acquired by the United States. That summer, the Constitutional Convention drafted the defining document of the American Republic. A bargain struck between both bodies outlawed slavery north of the Ohio River, at the same time giving Southern states Congressional and Electoral College representation based on population figures that included slaves--valued at three-fifths of a free white citizen. Because of this agreement, the western lands acquired from Great Britain after the Revolutionary War were divided into slave and free states, a compromise which precipitated the Civil War 74 years later. For years some historians denied that this political deal took place. Drawing on contemporary letters and documents, this detailed analysis re-examines the Ordinance and how Congress silently permitted the South's "peculiar institution" to move westward.