The keyword term "patriots day holiday states" is a noun phrase. The primary element, or head noun, which constitutes the main point, is the word "states". The preceding words, "Patriots Day holiday," function collectively as a compound modifier or adjectival phrase that specifies the category of states being referenced.
In this grammatical construction, the nouns "Patriots Day" (a proper noun for the holiday) and "holiday" (a common noun) act together as a noun adjunct. This means they are used like an adjective to describe the primary noun, "states." This adjectival phrase answers the question, "Which states?" The phrase identifies a specific group of states defined by their official recognition of a particular event, rather than describing a state that is itself a holiday.
The practical application of this phrase is to identify the specific U.S. states where Patriots' Day is an official, legally recognized public holiday. Historically and most notably, this includes Massachusetts and Maine. More recently, Connecticut and Wisconsin have also passed legislation to observe the day, thereby joining the specific group designated by this term.
