With a Cook Partisan Voting Index rating of D+6, it is the least Democratic district in Massachusetts, a state with an all-Democratic congressional delegation.

[2] Redistricting after the 2010 census eliminated Massachusetts's 10th congressional district; the 9th covers much of the old 10th's eastern portion.

"[5] 1862: "The towns of Ashburnham, Auburn, Barre, Boylston, Brookfield, Charlton, Clinton, Douglas, Dudley, Fitchburg, Gardner, Grafton, Holden, Hubbardston, Lancaster, Leicester, Leominster, Millbury, New Braintree, North Brookfield, Oakham, Oxford, Paxton, Princeton, Rutland, Shrewsbury, Southbridge, Spencer, Sterling, Sturbridge, Sutton, Templeton, Webster, West Boylston, Westminster, and Winchendon, and the city of Worcester, in the county of Worcester.

[11] 1977: "Norfolk County: Towns of Canton, Dedham, Dover, Needham, Norwood, Walpole, and Westwood.

Norfolk County: Towns of Canton, Dedham, Needham, Norwood, Stoughton, and Westwood.