Final answer:
Substantial opposition to the Constitution in the most populous states came from New York, Massachusetts, and Pennsylvania, where concerns about a strong central government, the balance of power, and individual rights led to intense debates between Federalists and Anti-Federalists.
Step-by-step explanation:
Opposition to the Constitution came from substantial majorities in some of the most populous states during the ratification process. In particular, three states where this opposition was most evident were New York, Massachusetts, and Pennsylvania. These states had significant power and wealth at stake and were wary of losing autonomy to a strong central government.
In Pennsylvania, opposition stemmed from the belief that all people, not just property owners, should have a say in the government, which reflected the state's adoption of a more democratic constitution during the Revolutionary Era. Massachusetts, on the other hand, adopted a more conservative constitution and faced internal conflict between elitists and democrats who called for dispersing power among the people. New York, being another large and influential state, feared the implications of centralization and the potential burdens of taxation and warfare imposed by a strong federal government.
Overall, these three states represented crucial battlegrounds where the Federalists, seeking to support a stronger national government, and the Anti-Federalists, fearing potential tyranny and loss of individual rights, vied for influence. The debates and discussions highlighted the intense scrutiny and skepticism that surrounded the proposed Constitution before its ultimate ratification.