Massachusetts's 3rd congressional district (MA-03)
Massachusetts's 3rd congressional district (MA-03) covers parts or all of Middlesex County, Essex County and Worcester County, and 50 ZIP codes (41 wholly inside it). Its 2020 population was 781,102. This is the map in force for the November 3, 2026 election.
Who represents MA-03
| Office | Member | Contact |
|---|---|---|
| U.S. Representative (MA-03) | Lori Trahan (D) | 202-225-3411 |
| U.S. Senator | Edward J. Markey (D) | 202-224-2742 · contact form |
| U.S. Senator | Elizabeth Warren (D) | 202-224-4543 · contact form |
Officials serving now (members of Congress until January 3, 2027). Sources: Members of Congress: the @unitedstates project, congress-legislators (CC0).
Counties
| County | Share of the county's residents in MA-03 |
|---|---|
| Middlesex County | 26% |
| Essex County | 26% |
| Worcester County | 16% |
ZIP codes
Percentages mark ZIPs only partly in MA-03: the share of that ZIP's residents inside it.
- 01420 (100%)
- 01430
- 01431
- 01432
- 01434
- 01440 (99%)
- 01450
- 01451
- 01460
- 01462
- 01463
- 01464
- 01469
- 01473 (92%)
- 01474
- 01475
- 01503
- 01510
- 01523
- 01561
- 01718
- 01719
- 01720
- 01731 (<0.1%)
- 01740
- 01741
- 01742
- 01749
- 01752
- 01773 (0.8%)
- 01775 (100%)
- 01821 (41%)
- 01824
- 01826
- 01827
- 01830
- 01832
- 01835
- 01840
- 01841
- 01843
- 01844
- 01850
- 01851
- 01852 (100%)
- 01854
- 01862 (98%)
- 01863
- 01879
- 01886
Towns
Acton town, Ashburnham town, Ashby town, Ayer town, Berlin town, Bolton town, Boxborough town, Carlisle town, Chelmsford town, Clinton town, Concord town, Dracut town, Dunstable town, Fitchburg city, Gardner city, Groton town, Harvard town, Haverhill city, Hudson town, Lancaster town, Lawrence city, Littleton town, Lowell city, Lunenburg town, Marlborough city, Methuen city, Pepperell town, Shirley town, Stow town, Townsend town, Tyngsborough town, Westford town, Winchendon town, Westminster town and Billerica town.
Get this in your AI agent
Your agent can draw every precinct in MA-03, or list them with population shares (related_geographies). Add https://boundarymcp.com/mcp to Claude, ChatGPT, Cursor or Codex (free, no key; how), then:
get_boundaries(id="us:congressional_district:2503", children_level="precinct", include_districts=True)