Mass. Gen. Laws ch. 57 § 1
For the purpose of electing representatives in the Congress of the United States and delegates and alternate delegates to the national conventions of political parties, until otherwise provided by law, the commonwealth is divided into the following 9 districts, each of which shall elect 1 representative:
First Congressional District - Consisting of the cities and towns in Berkshire county; the towns of Ashfield, Bernardston, Buckland, Charlemont, Colrain, Conway, Hawley, Heath, Leyden, Monroe, Rowe and Shelburne, all in the county of Franklin; the cities of Chicopee, Holyoke, Springfield, West Springfield and Westfield, and the towns of Agawam, Blandford, Brimfield, Chester, East Longmeadow, Granville, Hampden, Holland, Longmeadow, Ludlow, Monson and Montgomery, precincts 1, 2, 3 and 4 of the town of Palmer and the towns of Russell, Southwick, Tolland, Wales and Wilbraham, all in the county of Hampden; the city of Easthampton and the towns of Chesterfield, Cummington, Goshen, Granby, Huntington, Middlefield, Plainfield, South Hadley, Southampton, Westhampton, Williamsburg and Worthington, all in the county of Hampshire; the towns of Brookfield, Charlton, Dudley, East Brookfield, Southbridge, Sturbridge and Warren, all in the county of Worcester.
Second Congressional District - Consisting of the towns of Deerfield, Erving, Gill, Greenfield, Leverett, Montague, New Salem, Northfield, Orange, Shutesbury, Sunderland, Warwick, Wendell and Whately, all in the county of Franklin; sub-precinct 1A of the town of Palmer, in the county of Hampden; the city of Northampton and the towns of Amherst, Belchertown, Hadley, Hatfield, Pelham and Ware, all in the county of Hampshire; precinct 5 and sub-precinct 4A of the town of Bellingham, in the county of Norfolk; the cities of Leominster and Worcester and the towns of Athol, Auburn, Barre, Blackstone, Boylston, Douglas, Grafton, Hardwick, Holden, Hubbardston, Leicester, Mendon, Millbury, Millville, New Braintree, North Brookfield, Northborough, Northbridge, Oakham, Oxford, Paxton, Petersham, Phillipston, Princeton, Royalston, Rutland, Shrewsbury, Spencer, Sterling, Sutton, Templeton, Upton, Uxbridge, Webster, West Boylston, West Brookfield, Westborough and precinct 1 of the town of Winchendon, all in the county of Worcester.
Third Congressional District - Consisting of the cities of Haverhill, Lawrence and Methuen and precincts 2, 3, 4, 5, 6, 7 and 9 of the town of Andover, all in the county of Essex; the cities of Lowell and Marlborough and the towns of Acton, Ashby, Ayer, Boxborough, Carlisle, Chelmsford, Concord, Dracut, Dunstable, Groton, Hudson, Littleton, Maynard, Pepperell, Shirley, Stow, precinct 1 of the town of Sudbury and the towns of Townsend, Tyngsborough and Westford, all in the county of Middlesex; the cities of Fitchburg and Gardner and the towns of Ashburnham, Berlin, Bolton, Clinton, Harvard, Lancaster, Lunenburg, Westminster and precincts 2 and 3 and sub-precinct 1A of the town of Winchendon, all in the county of Worcester.
Fourth Congressional District - Consisting of the city of Attleboro, precinct C of ward 4, precinct C of ward 5, sub-precincts B1 of ward 5 and C1 of ward 6 and wards 7, 8 and 9 of the city of Fall River and the city of Taunton and the towns of Berkley, Dighton, Easton, Freetown, Mansfield, North Attleborough and Norton, precincts 3 and 4 and sub-precincts 1A and 2A of the town of Raynham and the towns of Rehoboth, Seekonk, Somerset and Swansea, all in the county of Bristol; the city of Newton and the town of Hopkinton, both in the county of Middlesex; precincts 1, 2, 3 and 4 of the town of Bellingham and the towns of Brookline, Dover, Foxborough, Franklin, Medfield, Medway, Millis, Needham, Norfolk, Plainville, Sharon, Wellesley and Wrentham, all in the county of Norfolk; the town of Lakeville in the county of Plymouth; the towns of Hopedale and Milford, both in the county of Worcester.
Fifth Congressional District - Consisting of the cities of Malden, Medford and Melrose, precincts 2 and 3 of ward 4, wards 6, 7, 8 and 9, sub-precinct 2A of ward 3 and precincts 1 and 2 of ward 10 of the city of Cambridge, the cities of Waltham and Woburn and the towns of Arlington, Ashland, Belmont, Framingham, Holliston, Lexington, Lincoln, Natick, Sherborn and Stoneham, precincts 2, 3, 4 and 5 and sub-precinct 1A of the town of Sudbury and the towns of Watertown, Wayland, Weston and Winchester, all in the county of Middlesex; the city of Revere and the town of Winthrop, both in the county of Suffolk; and the town of Southborough in the county of Worcester.
Sixth Congressional District - Consisting of the cities of Beverly, Gloucester, Lynn, Newburyport, Peabody and Salem and precincts 1 and 8 and sub-precinct 7A of the town of Andover and the towns of Amesbury, Boxford, Danvers, Essex, Georgetown, Groveland, Hamilton, Ipswich, Lynnfield, Manchester-by-the-Sea, Marblehead, Merrimac, Middleton, Nahant, Newbury, North Andover, Rockport, Rowley, Salisbury, Saugus, Swampscott, Topsfield, Wenham and West Newbury, all in the county of Essex; the towns of Bedford, Billerica, Burlington, North Reading, Reading, Tewksbury, Wakefield and Wilmington, all in the county of Middlesex.
Seventh Congressional District - Consisting of wards 1, 2, 3, precinct 1 of ward 4, ward 5, precinct 3 of ward 10, and ward 11 of the city of Cambridge and the cities of Everett and Somerville, all in the county of Middlesex; wards 1 and 2, precincts 7 and 8 of ward 3, ward 4, precincts 1, 2, sub-precinct 2A, 6, 7, 8, 9 and 10 of ward 5, precinct 10 of ward 7, wards 8, 9 and 10, precincts 1, 2, 3, 4, 5, 6, 7 and 8 of ward 11, ward 12, precincts 1, 2, 4, 5, 6, 8 and 9 of ward 13, wards 14 and 15, precincts 1, 3, 4, 6, 8 and 11 of ward 16, wards 17 and 18, precincts 7, 10, 11, 12 and 13 of ward 19, precinct 3 of ward 20, and wards 21 and 22 of the city of Boston and the city of Chelsea, both in the county of Suffolk; and precincts 1, 5 and 10 of the town of Milton and the town of Randolph, both in the county of Norfolk.
Eighth Congressional District - Consisting of precincts 1 and 2 of the town of Raynham, in the county of Bristol; the towns of Avon, Braintree, Canton, Cohasset, Dedham, Holbrook, precincts 2, 3, 4, 6, 7, 8 and 9 of the town of Milton, the towns of Norwood, Stoughton, Walpole, Westwood and Weymouth and the city of Quincy, all in the county of Norfolk; the towns of Abington, Bridgewater, East Bridgewater, Hingham, Hull, Scituate, West Bridgewater, and Whitman and the city of Brockton, all in the county of Plymouth; and precincts 1, 2, 3, 4, 5 and 6 of ward 3, precincts 3, 4, 5 and 11 of ward 5, ward 6, precincts 1, 2, 3, 4, 5, 6, 7, 8 and 9 of ward 7, precincts 9 and 10 of ward 11, precincts 3, 7 and 10 of ward 13, precincts 2, 5, 7, 9, 10 and 12 of ward 16, and precincts 1, 2, 3, 4, 5, 6, 8 and 9 of ward 19 and precincts 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20 of ward 20 of the city of Boston, in the county of Suffolk.
Ninth Congressional District - Consisting of the cities and towns in the counties of Barnstable, Dukes County and Nantucket; the towns of Acushnet, Dartmouth, Fairhaven and Westport, wards 1, 2, 3, precincts A and B of ward 4, precincts A and B of ward 5 and ward 6 of the city of Fall River and the city of New Bedford, all in the county of Bristol; and the towns of Carver, Duxbury, Halifax, Hanover, Hanson, Kingston, Marion, Marshfield, Mattapoisett, Middleborough, Norwell, Pembroke, Plymouth, Plympton, Rochester, Rockland and Wareham, all in the county of Plymouth.
Mass. Gen. Laws ch. 57, § 1