The core of the keyword term is the proper noun "Patriots' Day." As a complete search query, the interrogative clause functions as a noun phrase that defines the topic. The holiday is officially observed on the third Monday in April in the states of Massachusetts, Maine, and Wisconsin. While Connecticut also has an observance, it is not an official public holiday there.
The date is historically rooted in the Battles of Lexington and Concord, which occurred on April 19, 1775, and initiated the American Revolutionary War. The holiday was originally celebrated on the fixed date of April 19. However, to create a three-day weekend, Massachusetts moved the observance to the third Monday in April in 1969, a practice subsequently adopted by Maine. This shift mirrors the logic of the federal Uniform Monday Holiday Act, although Patriots' Day itself remains a state holiday.
In practice, the third Monday in April can fall on any date from April 15 to April 21. The date is most famously associated with the running of the Boston Marathon, an event held on Patriots' Day annually since 1897. As a state-level commemoration, its observation, including closures of schools and government offices, is primarily confined to the celebrating states and is not recognized as a federal holiday nationwide.
