99chambers

U.S. House seat · lines in effect since 2022

Massachusetts's 3rd District

A district of about 791,000 people, 23% Hispanic, 40% of adults with a bachelor's degree. It votes D+21.5 relative to the nation for president.

Lori Trahan (D) · since Jan 3, 2019Next election Nov 7, 2028The 2026 race →
MA-3

Source: 2026 results: civicAPI; boundaries: Census Bureau TIGER/LineUpdated Nov 7, 2026, 3:01 PM ET

Where it sits among all 435 seats

Every U.S. House seat by partisan lean, from most Democratic to most Republican. Lean is the seat's presidential vote on current lines, relative to the nation.

D+21.5115th most
Democratic
Most DemocraticMost Republican218th seat · the majority line758264MA-319

Labels below the bar mark 8 other seats in Massachusetts.

Source: 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET

Every race on these lines

Results recomputed from precinct returns as if today's boundaries had always existed, so years compare like for like.

20222026
U.S. HouseD+27.1D+36.8

Outlined: the race for this seat itselfBlank: no race that year

Source: 99chambers results archive: precinct results allocated to current lines; 2026: civicAPIUpdated Nov 7, 2026, 3:01 PM ET

Who lives here, compared

Grey bars show the spread of all 435 seats. Small marks are other seats in Massachusetts. The black marker is MA-3.

Adults with a bachelor's degree40% 72nd pct · 8th of 9 in MA

Higher than 72% of seats.

White adults without a degree35% 45th pct · 6th of 9 in MA

Lower than 55% of seats.

Hispanic residents23% 71st pct · 1st of 9 in MA

Higher than 71% of seats.

Black residents4% 29th pct · 6th of 9 in MA

Lower than 71% of seats.

Asian residents8% 79th pct · 4th of 9 in MA

Higher than 79% of seats.

People per square mile1,015 68th pct · 5th of 9 in MA

Denser than 68% of seats.

Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current linesUpdated Oct 13, 2026, 5:06 AM ET

Seats most like this one

Nearest seats on demographics, density and lean.

CA-51
28% Hispanic · 41% college gradsD+20.0Held DUT-1
25% Hispanic · 37% college gradsD+24.6Held DRI-1
38% college gradsD+24.0Held DIL-10
25% Hispanic · 46% college gradsD+23.4Held D

Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current lines; 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET

Who has held it

These lines took effect in 2022.

  1. Lori Trahan (D)
    2023– · Won 2022 by 27.1, 2024 unopposed, 2026 by 36.8

Source: Past results: 99chambers results archive (MEDSL, Klarner, state election offices)