What was the first constitution used by the United States from 1781 until it was replaced in 1789?

The Articles of Confederation were the first constitution used by the United States.

The Articles were finalized by the Continental Congress on November 15, 1777, and took effect on March 1, 1781, after all thirteen states had ratified them. Their formal title was the Articles of Confederation and Perpetual Union. The document created a league of states that retained substantial sovereignty while granting limited powers to a central Congress.

Under the Articles, Congress could conduct diplomacy, declare war, make treaties, and manage western territories. It lacked several powers associated with the later federal government, including broad authority to tax individuals directly and regulate interstate commerce. Financial and administrative weaknesses became increasingly apparent after the Revolutionary War.

The Constitutional Convention met in Philadelphia in 1787 to address those problems. Rather than merely amend the Articles, delegates drafted a new Constitution. The Constitution replaced the Articles on March 4, 1789, creating the federal government still used today.