Mass. Gen. Laws ch. 54 § 66
The state ballot boxes shall be used for receiving the ballots in state and city elections, and in town elections where official ballots are used. The election officers at each polling place shall, at the opening of the polls and before any ballots are received, publicly open the ballot box, and ascertain by personal examination, and publicly show, that the same is empty, and shall immediately thereafter lock or fasten the box. The clerk of the precinct, polling place or town shall make a record of the condition of the ballot box register and, if a key is used, it shall be retained by the police officer or constable at the polling place. The ballot box shall not, after it is shown to be empty, be removed from public view until all ballots have been removed therefrom and the box has been relocked or sealed. The ballot box shall not be opened nor any ballot removed therefrom until the polls are closed; but in order to make room for ballots, the presiding officer may, in the presence of all the election officers, open the box and pack and press down the ballots therein.
The presiding officer of each polling place shall have charge of the ballot box and ballot box seal, and shall, at the close of each election, return the same, either personally or by a police officer or constable in attendance at the polling place, to the city or town clerk.
Except as hereinafter provided, if it becomes impossible to use the state ballot box, the voting shall proceed in such manner as the presiding officer shall direct, and in such case the clerk shall record the reason why such ballot box is not used, and shall enclose an attested copy of such record in the envelope with the ballots cast. The provisions as to the use and custody of the state ballot box shall, so far as applicable, apply to the ballot box substituted therefor.
If it becomes impossible for voting to proceed because the ballot box is too full, the presiding officer, in the presence of a majority of the other election officers, shall open the ballot box, remove the ballots therefrom, without counting them, except that they may be divided into convenient packages, and shall place them in a container of fiber, wood, or metal. He shall then cause the container to be tied up lengthwise and crosswise with heavy twine securely tied, and the knot shall be sealed with stationer's sealing wax. Any election officer who so desires may affix his private seal to the container in such a way as to indicate later whether it has been opened. The container, with the uncounted ballots, shall not be removed from the polling place, but shall remain beside the ballot box, in full view of the voters and the election officers, until the polls close, when the container shall be opened in order to count the votes.
Mass. Gen. Laws ch. 54, § 66