The United States ratified the Articles of Confederation in 1781.
The Articles served as the first written constitution of the United States. The Second Continental Congress approved the text in 1777, but all 13 states did not ratify it until March 1, 1781, when Maryland became the final state to consent.
Under the Articles, the national government had authority over diplomacy, war, and western territories, but it lacked important powers such as the ability to impose taxes directly. Each state had one vote in Congress regardless of population.
The Articles remained in force until the Constitution replaced them in 1789. The years 1777 and 1781 are easy to confuse: 1777 was the year Congress approved the Articles, while 1781 was the year the states completed ratification.