Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 81, § 6

The department may alter the location of a state highway in a city or town by filing a plan thereof and a certificate that the department has laid out and taken charge of said state highway, as altered in accordance with said plan, in the office of the county commissioners for the county where said highway is situated, and by filing a copy of the plan or location as altered in the office of the clerk of such city or town.