Constitution of the United States

Delegates meeting in Philadelphia in 1787 had initially been convened to revise the Articles of Confederation, but the convention developed a new plan for national government. After debate and compromise, delegates signed the Constitution on 17 September 1787 and submitted it to state ratifying conventions. Article VII specified that ratification by nine states would establish the Constitution among the states ratifying it. New Hampshire became the ninth state to ratify on 21 June 1788; the new federal government began operating in 1789.

The Preamble states purposes that include forming a more perfect union, establishing justice and securing liberty. The Constitution has seven original articles. Article I vests federal legislative powers in a bicameral Congress, consisting of the Senate and House of Representatives; Article II establishes the presidency and executive branch; and Article III establishes the federal judiciary. Articles IV–VII address relations among states, amendment, constitutional supremacy and ratification. The arrangement divides authority between the national government and states and separates federal powers among branches, with checks that allow each branch to constrain aspects of the others.

Article V provides routes for proposing and ratifying amendments. The first ten amendments, collectively called the Bill of Rights, were ratified on 15 December 1791. They address protections including religious exercise, speech, press and assembly; criminal procedure; and limits on government power. Later amendments have changed constitutional rules and protections, including abolishing slavery, establishing equal protection and due process guarantees, and extending voting rights. There are 27 ratified amendments.

The Constitution's text supplies the framework for government, but its meaning and application have also developed through legislation, political practice and judicial interpretation. The Supreme Court and other courts resolve constitutional questions in cases, while amendment provides a formal route for changing the text. Disputes over the division of powers, individual rights and the meaning of constitutional provisions remain part of U.S. public life.