The keyword term "Patriot Day" functions as a proper noun. It is the official name of the annual observance in the United States on September 11. It is also formally known by the designation "National Day of Service and Remembrance."
This observance is frequently and incorrectly confused with "Patriots' Day," a separate holiday with a similar name. Patriot Day was established by Public Law 107-89 on December 18, 2001, to remember the nearly 3,000 people killed in the terrorist attacks of September 11, 2001. In contrast, Patriots' Day is a state holiday observed on the third Monday of April in Massachusetts, Maine, and Wisconsin. It commemorates the Battles of Lexington and Concord, the first armed conflicts of the American Revolutionary War in 1775.
In summary, Patriot Day (September 11) and Patriots' Day (April) are distinct proper nouns referring to entirely different events in American history. The former is a solemn national day of remembrance for a 21st-century tragedy, while the latter is a regional holiday celebrating the start of the nation's fight for independence. Recognizing the distinction is crucial for accurate historical and civic discourse.
