The keyword term functions as a noun phrase. "Patriots Day" is the core noun, modified by the context of the entire clause which acts as the subject of the inquiry. The main point of the article will be to define and clarify the geographical scope of this noun.
Patriots' Day is not an exclusive holiday to Massachusetts. It is also an official state holiday in Maine. The reason for this shared observance is historical; Maine was a district of Massachusetts until it achieved statehood in 1820, and thus it shares the holiday's origins. Additionally, Wisconsin observes April 19 as a special observance day in its public schools, though it is not a public holiday where government offices close. Similarly, Florida law designates April 19 as a day of remembrance, requiring schools to provide instruction on the topic.
The distinction lies in the level of observance. In Massachusetts and Maine, it is a full legal holiday celebrated on the third Monday of April, resulting in the closure of schools and state offices. This date also accommodates the running of the Boston Marathon. In contrast, Wisconsin and Florida's recognition occurs on the specific historical date of April 19 and is primarily educational in nature, mandated for schools but not impacting the general public or private businesses in the same way. Therefore, while the holiday is most famously associated with Massachusetts, its official recognition in varying forms extends to several other states.