A. Except as otherwise specifically limited by general law or special act, the governing body of each county, city, or town may provide by ordinance for the election of its members on any of the following bases: (i) at large from the county, city, or town; (ii) from single-member or multi-member districts or wards, or any combination thereof; or (iii) from any combination of at-large, single-member, and multi-member districts or wards. A change in the basis for electing the members of the governing body shall not constitute a change in the form of county government.

B. If the members are elected from districts or wards and other than entirely at large from the locality, the districts or wards shall be composed of contiguous and compact territory and shall be so constituted as to give, as nearly as is practicable, representation in proportion to the population of the district or ward. In 1971 and every 10 years thereafter, the governing body of each such locality shall reapportion the representation among the districts or wards, including, if the governing body deems it appropriate, increasing or diminishing the number of such districts or wards, in order to give, as nearly as is practicable, representation on the basis of population.

C. For the purposes of redistricting and reapportioning representation in 2001 and every 10 years thereafter, the governing body of a county, city, or town shall use the most recent decennial population figures for such county, city, or town from the United States Bureau of the Census, which figures are identical to those from the actual enumeration conducted by the United States Bureau of the Census for the apportionment of representatives in the United States House of Representatives, except that the census data for these redistricting and apportionment purposes will not include any population figure that is not allocated to specific census blocks within the Commonwealth, even though that population may have been included in the apportionment population figures of the Commonwealth for the purpose of allocating United States House of Representatives seats among the states. The governing body of any county, city, or town may elect to exclude the adult inmate population of any federal, state, or regional adult correctional facility located in the locality from the population figures used for the purposes of the decennial reapportionment and redistricting. The adult inmate population so excluded shall be based on information provided by the facility as to the adult inmate population at the facility on the date of the decennial census.

D. Notwithstanding any other provision of general law or special act, the governing body of a county, city, or town shall not reapportion the representation in the governing body at any time other than that required following the decennial census, except as (i) provided by law upon a change in the boundaries of the county, city, or town that results in an increase or decrease in the population of the county, city, or town of more than one percent, (ii) the result of a court order, (iii) the result of a change in the form of government, or (iv) the result of an increase or decrease in the number of districts or wards other than at-large districts or wards. The foregoing provisions notwithstanding, the governing body subsequent to the decennial redistricting may adjust district or ward boundaries in order that the boundaries might coincide with state legislative or congressional district boundaries; however, no adjustment shall affect more than five percent of the population of a ward or district or 250 persons, whichever is lesser. If districts created by a reapportionment enacted subsequent to a decennial reapportionment are invalid under the provisions of this subsection, the immediately preexisting districts shall remain in force and effect until validly reapportioned in accordance with law.

1995, c. 249; 2000, c. 884; 2001, Sp. Sess. I, c. 6; 2002, c. 127; 2012, c. 357; 2013, c. 483.