Flag Day: Exploring the History and Meaning of a National Symbol Library of Congress sent this bulletin at 05/15/2012 05:35 PM EDT You are subscribed to Teaching with the Library Blog for Library of Congress. This information has recently been updated, and is now available. Flag Day: Exploring the History and Meaning of a National Symbol 05/15/2012 05:00 PM EDT What is Flag Day? It’s a great opportunity to help students discover the history and meaning of an important national symbol.