Mass. Gen. Laws ch. 90, § 6B: One number plate; display

Section 6B. Notwithstanding any contrary provision of law, the registrar may issue but one number plate, instead of two, for certain motor vehicles or for all motor vehicles. Such plate shall be displayed at the rear of the vehicle for which it is issued, and all consistent provisions of law or of rules and regulations relating to number plates shall apply to such plate.