holidays September 17, 2024 4:23 pm What is Constitution Day? Constitution day is a federal holiday that commemorates the signing of the U.S. Constitution in 1787. US & World Videos 1:44 Deputy injured, large police presence in National City 1:07 More than 50 people stranded on roof of Tennessee hospital flooded by Helene 3:42 Brow Bootcamp: How to pick the right product type for you 2:30 Design The Backyard of Your Dreams With System Pavers 1:02 WATCH: Aerial images show Helene's trail of destruction in Florida