This Day in History: US Constitution Is Ratified June 21, 1788 The document creating the U.S. government as it is known today was ratified nearly a year after being written. In response to mounting debt and other problems created by the Articles of Confederation, the Second Constitutional Convention was held in Philadelphia over the course of three months in 1787. During these three months, delegates crafted the Constitution. New Hampshire was the ninth and final state to ratify the Constitution. The first ten amendments to the Constitution — known as the Bill of Rights — were ratified in 1791.