The Articles of Confederation took effect in 1781.
The Articles were finalized by the Continental Congress in 1777, but they required ratification by all 13 states. Maryland was the final state to ratify them, doing so on February 2, 1781. Congress received notice on March 1, and the Articles became the nation's operating framework.
They created a confederation in which the states retained substantial power. The national Congress could conduct diplomacy, make war, and manage certain western territories, but it lacked important powers such as direct taxation and broad authority to regulate trade. Those limitations made wartime finance and national coordination difficult.
The Articles were replaced by the Constitution in 1789. The Constitution did not merely amend the earlier document; it established a stronger federal structure with separate executive and judicial branches.