Eleven years after the Declaration of Independence announced the birth of the United States, the survival of the young country seemed in doubt. The War for Independence had been won, but economic depression, social unrest, interstate rivalries, and foreign intrigue appeared to be unraveling the fragile confederation. In early 1787, Congress called for a special convention of all the states to revise the Articles of Confederation. On September 17, 1787, after four months of secret meetings, the delegates to the Constitutional Convention emerged from their Philadelphia meetingroom with an entirely new plan of government–the U.S. Constitution–that they hoped would ensure the survival of the experiment they had launched in 1776.

They proposed a strong central government made up of three branches: legislative, executive, and judicial; each would be perpetually restrained by a sophisticated set of checks and balances. They reached compromises on the issue of slavery that left its final resolution to future generations. As for ratification, they devised a procedure that maximized the odds: the Constitution would be enacted when it was ratified by nine, not thirteen, states. The Framers knew they had not created a perfect plan, but it could be revised. The Constitution has been amended twenty-seven times and stands today as the longest-lasting written constitution in the world.

On September 17, 1787, two days after the final vote, the delegates signed the engrossed parchment shown in the Rotunda's centerpiece case.