Final answer:
The U.S. Constitution went into effect after it was ratified by nine of the thirteen states through state ratifying conventions, following its approval by the Constitutional Convention. The ratification process was challenging and the addition of the Bill of Rights was crucial for gaining the support of key states.
Step-by-step explanation:
After the Constitution was approved on September 17, 1787, by the Constitutional Convention in Philadelphia, it needed to undergo a ratification process by the states before it could go into effect. According to Article VII of the Constitution, the document required the ratification from nine of the thirteen states. State ratifying conventions were organized where elected representatives would debate and ultimately vote to accept or reject the Constitution. The ratification struggle was intense and involved significant debate and persuasion, including the contributions of the Federalist Papers advocating for the new system of government.
Moreover, dissatisfaction with the Constitution led to the drafting of the Bill of Rights, which comprises the first 10 Amendments, to ensure protections of individual liberties. This action was essential for securing the ratification from key states. The Constitution officially went into effect after New Hampshire became the ninth state to ratify it on June 21, 1788. However, the full unification under the new document would come later, with subsequent states' ratifications, including Virginia's approval on June 25, 1788.