The U.S. Constitution was ratified through votes in the individual state legislatures. According to Article VII of the Constitution, it would go into effect when nine of the 13 state legislatures approved the document.
The Constitution was completed in September of 1787, after a three-month Constitutional Convention presided over by George Washington. Congress then called on the state legislatures to meet at ratification conventions to vote on it. Heated debate ensued. Alexander Hamilton, James Madison and John Jay put forth their arguments in favor of the Constitution in a series of essays called the Federalist Papers. The Anti-Federalists, who opposed the Constitution, objected to too much power in the central government and the lack of a bill of rights.
Ultimately, it took 10 months before nine state legislatures ratified the Constitution. Delaware became the first state to approve it with a unanimous vote on Dec. 7, 1787. Soon after, Pennsylvania, New Jersey, Georgia and Connecticut ratified the Constitution. With the ratification of the ninth state, New Hampshire, on June 22, 1788, the new Constitution became law. Virginia and New York both ratified the Constitution by narrow margins in June and July of 1788 respectively. North Carolina ratified the document in 1789, after Congress proposed a bill of rights. Rhode Island became the last state to approve the Constitution in May 1790 under threat of being ostracized as a foreign entity.