Massachusetts's 3rd congressional district is located in north-central and northeastern Massachusetts. The largest municipalities in the district are Lowell, Lawrence, Haverhill, Methuen, Billerica (partial), Fitchburg, and Marlborough.

Democrat Lori Trahan has represented the district since 2019.

Cities and towns in the district As of the 2021 redistricting, the 3rd district contains 35 municipalities:

Essex County (3)

Haverhill, Lawrence, Methuen

Middlesex County (21)

Acton, Ashby, Ayer, Billerica (part; also 6th), Boxborough, Carlisle, Chelmsford, Concord, Dracut, Dunstable, Groton, Hudson, Littleton, Lowell, Marlborough, Pepperell, Shirley, Stow, Townsend, Tyngsborough, Westford

Worcester County (11)

Ashburnham, Bolton, Berlin, Clinton, Fitchburg, Gardner, Harvard, Lancaster, Lunenburg, Winchendon, Westminster (part; also 2nd)

History of district boundaries After the 2010 census, the third district shifted from covering east-central Worcester County and western Norfolk and Bristol counties to covering northeastern Worcester County, northern and western Middlesex County, and northwestern Essex county. The old 3rd district area was largely split between the updated 2nd and 4th districts. Only Clinton and Marlborough carried over from the old 3rd district.

In the redistricting that occurred after the 2020 census, the boundaries of the third district only changed slightly from its previous iteration.

Recent election results from statewide races Year Office Results2008 PresidentObama 59% - 39% SenateKerry 64% - 36%2010 Senate (Spec.)Brown 58% - 42% GovernorBaker 48% - 43%2012 PresidentObama 58% - 42% SenateBrown 51% - 49%2014 SenateMarkey 58% - 42% GovernorBaker 52% - 43%2016 PresidentClinton 57% - 35%2018 SenateWarren 57% - 39% GovernorBaker 71% - 28% Secretary of the CommonwealthGalvin 69% - 28% Attorney GeneralHealey 67% - 33% Treasurer and Receiver-GeneralGoldberg 65% - 31% AuditorBump 57% - 36%2020 PresidentBiden 62% - 35% SenateMarkey 64% - 35%2022 GovernorHealey 61% - 37% Secretary of the CommonwealthGalvin 65% - 32% Attorney GeneralCampbell 60% - 40% AuditorDiZoglio 55% - 39%2024 PresidentHarris 58% - 39% SenateWarren 58% - 42%

List of members representing the district