From May 10, 1775, to 1783, the Pennsylvania State House served as the principal meeting place of the Second Continental Congress, a body of representatives from each of the thirteen British North American colonies. On June 14, 1775, delegates of the Continental Congress nominated George Washington as commander-in-chief of the Continental Army in the Assembly Room of the Pennsylvania State House. The United States Declaration of Independence was approved there on July 4, 1776, and the Declaration was read aloud to the public in the area now known as Independence Square.

The Congress continued to meet there until December 12, 1776 after which the Congress evacuated Philadelphia. During the British occupation of Philadelphia, the Continental Congress met in Baltimore, Maryland (December 20, 1776 to February 27, 1777). The Congress returned to Philadelphia from March 4, 1777, to September 18, 1777. In September 1777, the British Army again arrived to occupy Philadelphia, once again forcing the Continental Congress to abandon the State House. It then met in Lancaster, Pennsylvania, for one day (September 27, 1777) and in York, Pennsylvania, for nine months (September 30, 1777 to June 27, 1778), where the Articles of Confederation were approved in November 1777. The Second Continental Congress again returned to Independence Hall, for its final meetings, from July 2, 1778, to March 1, 1781. Under the Articles of Confederation, the Congress of the Confederation initially met in Independence Hall, from March 1, 1781, to June 21, 1783. However, as a result of the Pennsylvania Mutiny of 1783, Congress again moved from Philadelphia in June 1783 to Princeton, New Jersey, and eventually to other cities.

The Constitutional Convention took place in Philadelphia from May 25 to September 17, 1787. The delegates elected George Washington, proponent of a stronger national government, to become President of the convention. The result of the convention was the creation of the Constitution of the United States.