Mass. Gen. Laws ch. 43A § 4
Other than the officers designated in the by-laws of the town as town meeting members at large, the representative town meeting membership shall in each precinct consist of the largest number divisible by three which will admit of a representation thereof in the approximate proportion which the number of inhabitants therein bears to the total number of inhabitants in the town, and which will cause the total elected membership to be as nearly two hundred and forty as may be.
The registered voters in every precinct shall, at the first annual town election held after the establishment of such precinct, and the registered voters of any precinct affected by any revision of precincts at the first annual town election following such revision, conformably to the laws relative to elections not inconsistent with this chapter, elect by ballot the number of registered voters in the precinct, other than the officers designated in the by-laws as town meeting members at large, provided for in the first sentence of this section, to be town meeting members of the town. The first third, in the order of votes received, of members so elected shall serve three years, the second third in such order shall serve two years, and the remaining third in such order shall serve one year, from the day of the annual town meeting; in case of a tie vote affecting the division into thirds, as aforesaid, the members elected from the precinct shall by ballot determine the same; and thereafter, except as is otherwise provided herein, at each annual town election the registered voters of each precinct shall, in like manner, elect, for the term of three years, one third of the number of elected town meeting members to which such precinct is entitled, and shall at such election fill for the unexpired term or terms any vacancy or vacancies then existing in the number of elected town meeting members in such precinct.
The terms of office of all elected town meeting members from every precinct revised as aforesaid shall cease upon the election as hereinbefore provided of their successors. The town clerk shall, after every election of town meeting members, forthwith notify each such member by mail of his election.
Mass. Gen. Laws ch. 43A, § 4