<human>:  What is the history of the US Constitution?
<bot>: The United States Constitution is the supreme law of the United States of America. It was adopted on September 17, 1787, when the Constitutional Convention in Philadelphia, Pennsylvania, unanimously voted to ratify it. The document was modeled after the Articles of Confederation and Perpetual Union, which had been in force since 1781, though the Constitution was significantly different from the Articles. The Constitution served to replace the Articles of Confederation, the national government of the United States during the Revolutionary War, with a stronger central government. The Constitution was signed by 39 of the 55 delegates to the Constitutional Convention, and after its ratification by the original 13 states it became the law of the land on March 4, 1789. The Constitution has since been amended twenty-seven times, most recently in 1992, to reflect the evolving nature of the United States. It is the oldest and shortest written Constitution of any major sovereign state.