What geographical feature was the southern boundary of the Northwest Territory?

The southern boundary of the Northwest Territory was defined by the Ohio River. This river served as a critical geographical marker in the early organization of land in the United States after the American Revolution. The Northwest Ordinance of 1787 established the boundary lines for the territory, which included modern-day states such as Ohio, Indiana, Illinois, Michigan, Wisconsin, and part of Minnesota. The Ohio River functioned as a natural divider, influencing settlement patterns and governance during that period.

Other geographical features listed do not serve as the designated southern boundary of the Northwest Territory. The Mississippi River, while a significant waterway, was to the west of the territory in question, separating it from other regions. The Missouri River is located even further west and does not factor into the boundaries defined by the Northwest Ordinance. The Appalachian Mountains, spanning a significant area in the eastern United States, were not relevant as a southern boundary for the Northwest Territory, which was located to the northwest of these mountains.