Flag Day

commemorating the adoption of the U.S. flag in 1777 A flag day is a flag-related holiday, a day designated for flying a certain flag (such as a national flag) or a day set aside to celebrate a historical event such as a nation's adoption of its flag. Flag days are usually codified in national statutes passed by legislative bodies or parliaments; however, in some countries a decree or proclamation by the head of state or chief executive can also order a flag day. The statute or proclamation / decree may specify locations where flags are flown and how are they flown (for example, at full- or half-staff); alternatively, custom may prevail https://en.wikipedia.org/wiki/Flag_Day