Final answer:
The three major ordinances are The Land Ordinance of 1785, the Northwest Ordinance of 1787, as well as the Ordinance of 1784, which collectively established the framework for selling land, forming new states, and protecting settlers' rights.
Step-by-step explanation:
The three major ordinances passed by Congress dealing with the development of the territory were The Land Ordinance of 1785, the Northwest Ordinance of 1787, and the Ordinance of 1784.
The Land Ordinance of 1785 played a crucial role in the expansion of the United States. It divided the Northwest Territory into townships of six miles squared, which were further divided into thirty-six sections of 640 acres each, with one section set aside for schools. This law significantly impacted American land sales and developments west of the Appalachian Mountains.
The Northwest Ordinance of 1787 was one of the most significant accomplishments, establishing a system for the settlement and eventual statehood of new territories, while also banning slavery and providing a Bill of Rights for settlers.
The Ordinance of 1784, written by Thomas Jefferson, predates the other mentioned ordinances and directed the formation of new states with equal standing to the original states, from land below the Great Lakes.