On what date was the U.S. Constitution signed, a key founding milestone preceding America250?

The U.S. Constitution was signed on September 17, 1787, a key founding milestone preceding America250.

Delegates signed the Constitution at the Pennsylvania State House in Philadelphia, now known as Independence Hall. The Constitutional Convention had met there during the summer of 1787 to replace the weak Articles of Confederation with a stronger federal framework.

Thirty-nine delegates signed the completed document. George Washington presided over the convention, while James Madison played a major role in drafting and recording its proceedings. The Constitution then went to the states for ratification rather than taking effect immediately upon signing.

September 17 is now observed in the United States as Constitution Day and Citizenship Day. It is sometimes confused with June 21, 1788, when New Hampshire became the ninth state to ratify, and with March 4, 1789, when the new constitutional government began operating. America250 focuses on 1776, but the Constitution is a major neighboring milestone in the nation’s founding story.