The key term within the query, "Patriot Day," functions as a proper noun. It is the name of an annual observance in the United States held on September 11. This day commemorates the individuals killed in the terrorist attacks of September 11, 2001, and is officially known as Patriot Day and National Day of Service and Remembrance.
This observance should not be confused with "Patriots' Day," a different holiday celebrated on the third Monday of April in Massachusetts, Maine, and Wisconsin. Patriots' Day commemorates the anniversary of the Battles of Lexington and Concord, the first military engagements of the American Revolutionary War in 1775. The similar naming convention is a frequent source of confusion, but the two events honor completely different moments in United States history, separated by more than two centuries.
On Patriot Day (September 11), the flag of the United States is flown at half-staff at the White House and on all U.S. government buildings and establishments, both at home and abroad. Americans are also encouraged to display flags at half-staff from their homes. A moment of silence is traditionally observed at 8:46 a.m. Eastern Daylight Time, corresponding to the time the first plane struck the North Tower of the World Trade Center.
