Census tract · Middlesex County
Census Tract 3691, Middlesex County, Massachusetts
Census Tract 3691, GEOID 25017369100, in Middlesex County, Massachusetts, entirely within Waltham. 5,135 residents in the ACS 2020-2024 5-year estimates (±570); the 2020 Census counted 5,059.
Residents, 2020-2024
5,135
±570 (90% margin)
2020 Census count: 5,059
Median household income
$133,824
±$13,988 (90% margin)
Middlesex County: $130,847
Median home value
$780,900
±$44,494 (90% margin)
Middlesex County: $727,800
Median gross rent
$1,841
±$140 (90% margin)
Middlesex County: $2,201
Where is Census Tract 3691?
Census Tract 3691 is one of 357 census tracts in Middlesex County, Massachusetts. It covers 1.00 square miles of land, 5,044 residents per square mile in 2020. Its GEOID, 25017369100, names it uniquely (how tract numbers and GEOIDs work).
| Place | Share of the tract |
|---|---|
| Waltham | 100% |
5 census tracts border Census Tract 3691: Tract 3577 ($138,958), Tract 3688 ($104,608), Tract 3689.02 ($58,887), Tract 3690 and Tract 3701.01 ($123,902). 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 3691?
The 2020-2024 American Community Survey puts Census Tract 3691's population at 5,135 (±570) in 2,008 households; the 2020 Census counted 5,059 residents and 2,080 housing units.
| Measure | Tract 3691 | Waltham |
|---|---|---|
| Total population | 5,135±570 | 64,902 |
| Households | 2,008±193 | 25,498 |
| Average household size | 2.54±0.15 | 2.23 |
| Housing units | 2,094±189 | 26,728 |
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 3691?
The median resident of Census Tract 3691 is 44.3 years old; 19.3% are under 18 and 23.4% are 65 or older. The largest group is non-Hispanic white residents at 75.1%, then Hispanic or Latino residents (of any race) at 9.3%. 18.0% of residents were born outside the United States.
| Measure | Tract 3691 | Waltham |
|---|---|---|
| Median age | 44.3±2.1 | 34.4 |
| Under 18 years | 19.3%±4.1 pts | 13.6% |
| 65 years and over | 23.4%±2.6 pts | 15.8% |
| Hispanic or Latino (any race) | 9.3%±4.8 pts | 15.9% |
| White alone, not Hispanic | 75.1%±7.7 pts | 57.6% |
| Black or African American alone, not Hispanic | 7.5%±6.2 pts | 8.3% |
| Asian alone, not Hispanic | 4.1%±3.0 pts | 12.6% |
| American Indian and Alaska Native alone, not Hispanic | 0.0%±0.8 pts | 0.3% |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0%±0.8 pts | 0.1% |
| Two or more races, not Hispanic | 4.1%±2.1 pts | 4.3% |
| Some other race alone, not Hispanic | 0.0%±0.8 pts | 0.9% |
| Born outside the United States | 18.0%±7.5 pts | 26.3% |
| Speak a language other than English at home (age 5+) | 20.7%±7.8 pts | 32.3% |
| Civilian veterans (age 18+) | 5.2%±2.3 pts | 2.6% |
| With a disability | 4.8%±2.1 pts | 10.7% |
| No health insurance coverage | 0.2%±0.3 pts | 2.9% |
| High school graduate or higher (age 25+) | 94.2%±4.3 pts | 93.3% |
| Bachelor's degree or higher (age 25+) | 57.7%±7.3 pts | 57.3% |
| Graduate or professional degree (age 25+) | 21.6%±5.8 pts | 27.9% |
| Lived in the same house a year earlier | 92.9%±3.1 pts | 83.0% |
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 3691 earn?
Half of the 2,008 households in Census Tract 3691 earn less than $133,824 a year (±$13,988), against $130,847 across Middlesex County: 174th highest of the county's 350 tracts with a reliable estimate. 3.6% of residents live below the poverty line.
| Measure | Tract 3691 | Waltham |
|---|---|---|
| Median household income | $133,824±$13,988 | $120,216 |
| Mean household income | $166,803±$19,961 | $145,664 |
| Per capita income | $67,216±$9,293 | $58,449 |
| People below the poverty line | 3.6%±2.2 pts | 9.4% |
| Children under 18 below the poverty line | 2.9%±3.3 pts | 7.6% |
| Households receiving SNAP | 3.9%±3.8 pts | 7.0% |
| Households with a computer | 95.6%±3.4 pts | 95.6% |
| Households with a broadband subscription | 95.1%±3.4 pts | 94.0% |
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 3691?
Owners occupy 82.0% of Census Tract 3691's occupied homes and renters 18.0%. The median owner-occupied home is valued at $780,900 by its owner (±$44,494). The median renter pays $1,841 a month including utilities, and 23.3% of renters pay 35% or more of their income on rent.
| Measure | Tract 3691 | Waltham |
|---|---|---|
| Median home value (owner-occupied) | $780,900±$44,494 | $748,700 |
| Median gross rent | $1,841±$140 | $2,268 |
| Renters paying 35% or more of income on rent | 23.3%±13.5 pts | 35.7% |
| Median monthly owner costs, with a mortgage | $3,033±$256 | $3,076 |
| Owner-occupied homes | 82.0%±7.1 pts | 49.7% |
| Renter-occupied homes | 18.0%±7.1 pts | 50.3% |
| Housing units | 2,094±189 | 26,728 |
| Single-family detached homes | 80.7%±6.6 pts | 37.0% |
| Mobile homes | 0.0%±2.0 pts | 0.2% |
| Built 2020 or later | 0.0%±2.0 pts | 1.1% |
| Built 2010 to 2019 | 3.3%±3.3 pts | 6.4% |
| Built 1939 or earlier | 23.0%±7.1 pts | 28.3% |
| Households with no vehicle | 3.2%±2.4 pts | 8.6% |
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 3691 get to work?
66.1% of Census Tract 3691's workers drive alone and 25.7% work from home. The average trip to work takes 23.3 minutes.
| Measure | Tract 3691 | Waltham |
|---|---|---|
| In the labor force (age 16+) | 71.5%±4.9 pts | 68.5% |
| Unemployment rate | 5.0%±3.7 pts | 3.7% |
| Drove alone to work | 66.1%±7.8 pts | 53.0% |
| Carpooled | 5.8%±3.1 pts | 9.5% |
| Public transportation | 1.7%±1.8 pts | 4.5% |
| Walked | 0.2%±0.3 pts | 6.2% |
| Worked from home | 25.7%±6.2 pts | 24.2% |
| Mean travel time to work | 23.3 min±2.6 | 24.7 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 3691 compare with the other tracts in Middlesex County?
Among Middlesex County's tracts with a reliable estimate, Census Tract 3691 ranks as shown below (1 = highest).
| Measure | In Middlesex County | In Waltham |
|---|---|---|
| Population | 134th of 354 | 7th of 13 |
| Residents per square mile | 175th of 357 | 9th of 13 |
| Median household income | 174th of 350 | 4th of 11 |
| Per capita income | 182nd of 354 | 5th of 13 |
| Median home value | 155th of 350 | 6th of 13 |
| Median gross rent | 236th of 327 | 9th of 12 |
| Poverty rate | 201st of 223 | 9th of 9 |
| Bachelor's degree or higher | 200th of 354 | 5th of 13 |
| Median age | 90th of 354 | 3rd of 13 |
| Owner-occupied share | 79th of 351 | 2nd of 13 |
The tracts next to it on Middlesex County's income ladder
| Tract | Rank | Median household income |
|---|---|---|
| Tract 3241.01 | 171st | $135,147±$25,819 · within the margin of this tract |
| Tract 3364.03 | 172nd | $135,054±$27,486 · within the margin of this tract |
| Tract 3511.02 | 173rd | $134,375±$47,978 · within the margin of this tract |
| Tract 3691 | 174th | $133,824±$13,988 |
| Tract 3507.01 | 175th | $133,233±$39,975 · within the margin of this tract |
| Tract 3501.06 | 176th | $133,125±$35,738 · within the margin of this tract |
| Tract 3525 | 177th | $132,500±$27,969 · 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 3691?
2 of the 18 figures for Census Tract 3691 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