Final answer:
A territory becomes a state by growing its population, establishing defined boundaries, and creating a local government. This process culminates with Congress passing an Act of Admission, which grants the territory full statehood and representation in Congress.
Step-by-step explanation:
The three main stages a territory goes through to become a state are part of an established legal and practical process in the United States. Initially, a territory must have a sufficient population; for example, the Northwest Ordinance of 1787 required a minimum of 60,000 inhabitants. Furthermore, the territory must have well-defined and recognized boundaries. Once these criteria are met, the residents can petition Congress for statehood.
The second stage involves the establishment of a local government. If Congress approves the petition, the territorial residents may draft a state constitution, which serves as a blueprint for the local government's operation and ensures alignment with the U.S. Constitution. After the local government is operational, the territory acts similarly to a state, though still lacking full statehood status and benefits.
Finally, the third stage is the grant of full statehood by Congress. Once the local legislature or constitutional convention has agreed upon the constitution, the territory submits it to Congress for approval. If approved, Congress passes an Act of Admission, officially recognizing the new state. Upon acceptance, the new state has all the rights and responsibilities of statehood, including representation in Congress.