About this date
Constitution Signed
The U.S. Constitution was signed on September 17, 1787. This page provides a large time-since clock for the signing date and related U.S. history milestones.
How this countdown is calculated
- Date certainty: exact.
- Date maintenance: Fixed date.
- Time policy: event timezone.
Quick facts
- The U.S. Constitution was signed on September 17, 1787.
- Constitution Day is observed on September 17.
- The signing date is distinct from later ratification milestones.