Census tract · Middlesex County
Census Tract 3631.04, Middlesex County, Massachusetts
Census Tract 3631.04, GEOID 25017363104, in Middlesex County, Massachusetts, entirely within Acton. 6,422 residents in the ACS 2020-2024 5-year estimates (±570); the 2020 Census counted 6,259.
Residents, 2020-2024
6,422
±570 (90% margin)
2020 Census count: 6,259
Median household income
$155,150
±$14,158 (90% margin)
Middlesex County: $130,847
Median home value
$792,300
±$42,725 (90% margin)
Middlesex County: $727,800
Median gross rent
$1,417
±$164 (90% margin)
Middlesex County: $2,201
Where is Census Tract 3631.04?
Census Tract 3631.04 is one of 357 census tracts in Middlesex County, Massachusetts. It covers 5.88 square miles of land, 1,064 residents per square mile in 2020. Its GEOID, 25017363104, names it uniquely (how tract numbers and GEOIDs work).
| Place | Share of the tract |
|---|---|
| Acton | 100% |
8 census tracts border Census Tract 3631.04: Tract 3612 ($192,279), Tract 3613 ($211,161), Tract 3631.03 ($139,250), Tract 3631.05 ($125,833), Tract 3632.01 ($232,000), Tract 3632.02 ($200,625), Tract 3641.01 ($126,786) and Tract 3641.02 ($122,966). The figure in brackets is each tract's median household income.
Whether a tract counts as low- or moderate-income for bank lending (the Community Reinvestment Act) is set by the FFIEC against its metro area's family income: look it up in the FFIEC census geocoder.
Source: 2024 Gazetteer and 2020 block assignment files, U.S. Census Bureau · Census reference files
How many people live in Census Tract 3631.04?
The 2020-2024 American Community Survey puts Census Tract 3631.04's population at 6,422 (±570) in 2,398 households; the 2020 Census counted 6,259 residents and 2,312 housing units.
| Measure | Tract 3631.04 | Acton |
|---|---|---|
| Total population | 6,422 ±570 | 24,155 |
| Households | 2,398 ±205 | 9,409 |
| Average household size | 2.66 ±0.23 | 2.55 |
| Housing units | 2,398 ±205 | 9,575 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 Census P.L. 94-171 · Check it at data.census.gov
Who lives in Census Tract 3631.04?
The median resident of Census Tract 3631.04 is 44.9 years old; 24.5% are under 18 and 16.4% are 65 or older. The largest group is non-Hispanic white residents at 64.0%, then non-Hispanic Asian residents at 24.3%. 28.5% of residents were born outside the United States.
| Measure | Tract 3631.04 | Acton |
|---|---|---|
| Median age | 44.9 ±1.7 | 44.5 |
| Under 18 years | 24.5% ±3.2 pts | 23.2% |
| 65 years and over | 16.4% ±3.4 pts | 17.6% |
| Hispanic or Latino (any race) | 1.5% ±1.6 pts | 4.1% |
| White alone, not Hispanic | 64.0% ±6.7 pts | 58.9% |
| Black or African American alone, not Hispanic | 1.9% ±2.0 pts | 4.7% |
| Asian alone, not Hispanic | 24.3% ±5.0 pts | 25.5% |
| American Indian and Alaska Native alone, not Hispanic | 0.0% ±0.7 pts | 0.0% |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0% ±0.7 pts | 0.0% |
| Two or more races, not Hispanic | 5.6% ±3.8 pts | 5.2% |
| Some other race alone, not Hispanic | 2.8% ±2.9 pts | 1.7% |
| Born outside the United States | 28.5% ±5.8 pts | 28.8% |
| Speak a language other than English at home (age 5+) | 31.4% ±7.1 pts | 34.1% |
| Civilian veterans (age 18+) | 5.9% ±3.0 pts | 4.4% |
| With a disability | 11.3% ±3.4 pts | 9.1% |
| No health insurance coverage | 0.6% ±0.7 pts | 1.7% |
| High school graduate or higher (age 25+) | 96.6% ±3.2 pts | 98.0% |
| Bachelor's degree or higher (age 25+) | 77.6% ±4.9 pts | 79.5% |
| Graduate or professional degree (age 25+) | 48.1% ±5.2 pts | 47.6% |
| Lived in the same house a year earlier | 93.1% ±3.6 pts | 87.9% |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profiles DP02, DP05) · Check it at data.census.gov
What do households in Census Tract 3631.04 earn?
Half of the 2,398 households in Census Tract 3631.04 earn less than $155,150 a year (±$14,158), against $130,847 across Middlesex County: 119th highest of the county's 350 tracts with a reliable estimate.
| Measure | Tract 3631.04 | Acton |
|---|---|---|
| Median household income | $155,150 ±$14,158 | $158,230 |
| Mean household income | $197,878 ±$20,013 | $208,786 |
| Per capita income | $73,490 ±$7,924 | $81,425 |
| People below the poverty line | 4.0% ±2.7 pts | 3.4% |
| Children under 18 below the poverty line | 2.8% ±4.4 pts | 1.9% |
| Households receiving SNAP | 1.8% ±1.9 pts | 3.9% |
| Households with a computer | 97.0% ±4.7 pts | 98.3% |
| Households with a broadband subscription | 96.6% ±4.3 pts | 97.2% |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What does housing cost in Census Tract 3631.04?
Owners occupy 81.8% of Census Tract 3631.04's occupied homes and renters 18.2%. The median owner-occupied home is valued at $792,300 by its owner (±$42,725). The median renter pays $1,417 a month including utilities.
| Measure | Tract 3631.04 | Acton |
|---|---|---|
| Median home value (owner-occupied) | $792,300 ±$42,725 | $807,300 |
| Median gross rent | $1,417 ±$164 | $1,986 |
| Renters paying 35% or more of income on rent | 14.4% ±13.8 pts | 44.0% |
| Median monthly owner costs, with a mortgage | $3,849 ±$370 | $3,812 |
| Owner-occupied homes | 81.8% ±5.9 pts | 74.9% |
| Renter-occupied homes | 18.2% ±5.9 pts | 25.1% |
| Housing units | 2,398 ±205 | 9,575 |
| Single-family detached homes | 74.6% ±4.7 pts | 63.3% |
| Mobile homes | 0.0% ±1.8 pts | 0.0% |
| Built 2020 or later | 0.0% ±1.8 pts | 0.4% |
| Built 2010 to 2019 | 3.5% ±1.9 pts | 6.5% |
| Built 1939 or earlier | 10.9% ±6.0 pts | 8.8% |
| Households with no vehicle | 1.7% ±1.7 pts | 3.1% |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP04) · Check it at data.census.gov
How do people in Census Tract 3631.04 get to work?
48.4% of Census Tract 3631.04's workers drive alone and 44.1% work from home. The average trip to work takes 35.8 minutes.
| Measure | Tract 3631.04 | Acton |
|---|---|---|
| In the labor force (age 16+) | 69.9% ±4.3 pts | 69.7% |
| Unemployment rate | 2.6% ±2.3 pts | 4.7% |
| Drove alone to work | 48.4% ±8.6 pts | 52.7% |
| Carpooled | 3.0% ±1.9 pts | 5.2% |
| Public transportation | 2.2% ±1.5 pts | 3.3% |
| Walked | 1.9% ±1.8 pts | 2.0% |
| Worked from home | 44.1% ±9.0 pts | 35.9% |
| Mean travel time to work | 35.8 min ±5.6 | 34.6 min |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
How does Census Tract 3631.04 compare with the other tracts in Middlesex County?
Among Middlesex County's tracts with a reliable estimate, Census Tract 3631.04 ranks as shown below (1 = highest).
| Measure | In Middlesex County |
|---|---|
| Population | 55th of 354 |
| Residents per square mile | 305th of 357 |
| Median household income | 119th of 350 |
| Per capita income | 145th of 354 |
| Median home value | 152nd of 350 |
| Median gross rent | 300th of 327 |
| Bachelor's degree or higher | 85th of 354 |
| Median age | 71st of 354 |
| Owner-occupied share | 81st of 351 |
The tracts next to it on Middlesex County's income ladder
| Tract | Rank | Median household income |
|---|---|---|
| Tract 3184 | 117th | $155,909±$26,929 · within the margin of this tract |
| Tract 3324.02 | 118th | $155,417±$40,735 · within the margin of this tract |
| Tract 3631.04 | 119th | $155,150±$14,158 |
| Tract 3323 | 120th | $154,750±$54,722 · within the margin of this tract |
| Tract 3391.02 | 121st | $154,620±$36,045 · within the margin of this tract |
| Tract 3151 | 122nd | $153,942±$21,997 · within the margin of this tract |
"Within the margin": the two incomes differ by less than their combined 90% margins, so the survey cannot say which is higher and the ranks between them are not firm.
Source: PlainCities ranks computed from the American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) · How ranks are computed
How reliable are the figures for Census Tract 3631.04?
3 of the 18 figures for Census Tract 3631.04 on this page carry a coefficient of variation over 40% and are marked with a ring: they come from a small sample, so read them as rough.
A census tract's figures rest on a few hundred sampled households over five years, so its margins are wider than a city's. Two tracts differ only when the gap between them is larger than their combined 90% margin (the square root of the sum of the two squared margins). How to read a margin of error.
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026): margins of error as published · Check it at data.census.gov
How these figures are made: methodology and release checks · reading a margin of error · every state · corrections