The correct answer is A. Although the Northwest Ordinance of 1787 only dealt with the area north of the Ohio river, it influenced U.S. expansion in other areas by establishing procedures for how new states could be admitted to the Union.
The Northwest Order was unanimously approved on July 13, 1787. The main effect of the ordinance was the creation of the Northwest Territory as the first organized territory of the United States of the region south of the Great Lakes north and west of the Ohio River, and east of the Mississippi River.
Possibly the most important legislation that was passed by the members of the Continental Congress apart from the Declaration of Independence, it established the precedence by which the United States expanded westward through North America by the admission of new states rather than by the expansion of existing states. The prohibition of slavery in the territory made the Ohio River the border between the free territories and the slave territories around the Appalachians and the Mississippi River.
