Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 54, § 69

No persons except the election officers, supervisors, custodians of voting machines when acting in the course of their duties, the city or town clerks, and voters admitted for the purpose of voting, shall, during the progress of an election and until the public declaration of the vote, be permitted within the guard rail, unless authorized by the election officers for the purpose of keeping order and enforcing the law. Children, in the company of a voter, may be admitted within the guardrail unless the election officer in charge deems that the admittance of such child would disrupt the maintenance of order.