The Articles of Confederation became effective as the U.S. national framework on March 1, 1781.
The Articles were the first governing document of the United States and created a confederation of sovereign states. The Second Continental Congress approved them in 1777, but they did not take effect until Maryland became the final state to ratify them in 1781.
Under the Articles, Congress handled diplomacy, war, western lands, and some other national responsibilities. However, the central government could not directly tax individuals, regulate interstate commerce effectively, or compel states to provide money and troops. These weaknesses became increasingly visible after the Revolutionary War.
The Constitution replaced the Articles after the Constitutional Convention of 1787. The change did not occur immediately: the Constitution took effect after New Hampshire became the ninth state to ratify it in June 1788, and the new federal government began operating in 1789.