what document did the constitution replace?

The United States Constitution replaced the Articles of Confederation as the nation’s governing document.

Under the Articles of Confederation, the states held most of the power and the central government was very weak, which caused problems with taxation, defense, and coordination between states. When the Constitution was drafted in 1787 and then put into effect in 1789, it superseded the Articles by creating a stronger federal government with an executive (the president), a national court system, and clearer powers over taxation and national policy.