Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 41, § 110A

Any public office in any city or town may remain closed on any or all Saturdays as may be determined from time to time, in a city by the city council, subject to the provisions of the city charter, or, in a town, by vote of the town at a special or regular town meeting, and the provisions of section nine of chapter four shall apply in the case of such closing of any such office on any Saturday to the same extent as if such Saturday were a legal holiday.