The keyword phrase is an interrogative clause, with the interrogative adverb "when" establishing the primary function of the query: to identify a specific date. The resolution to this query is a noun phrase that specifies the exact day of the observance. For the year 2025, Patriots' Day will be observed on Monday, April 21.
This date is determined by state statutes in Massachusetts and Maine, which mandate that the holiday falls on the third Monday in April. The observance commemorates the anniversary of the Battles of Lexington and Concord, the initial armed conflicts of the American Revolutionary War on April 19, 1775. The holiday was originally observed on the fixed date of April 19 but was shifted to the third Monday in 1969 (in Massachusetts) to create a three-day weekend, a practice aligned with the federal Uniform Monday Holiday Act.
The practical application of this date is significant, most notably as it dictates the running of the Boston Marathon, an event traditionally held on Patriots' Day each year. As a public holiday in Massachusetts and Maine, state and local government offices, as well as public schools and many businesses, will be closed on April 21, 2025. It is not a federal holiday and is not officially observed in other states, making its cultural and civic impact highly regional.
