Census tract · Middlesex County
Census Tract 3686, Middlesex County, Massachusetts
Census Tract 3686, GEOID 25017368600, in Middlesex County, Massachusetts, entirely within Waltham. 5,688 residents in the ACS 2020-2024 5-year estimates (±693); the 2020 Census counted 5,856.
Residents, 2020-2024
5,688
±693 (90% margin)
2020 Census count: 5,856
Median household income
$125,625
±$16,661 (90% margin)
Middlesex County: $130,847
Median home value
$586,400
±$73,924 (90% margin)
Middlesex County: $727,800
Median gross rent
$2,122
±$129 (90% margin)
Middlesex County: $2,201
Where is Census Tract 3686?
Census Tract 3686 is one of 357 census tracts in Middlesex County, Massachusetts. It covers 0.43 square miles of land, 13,746 residents per square mile in 2020. Its GEOID, 25017368600, names it uniquely (how tract numbers and GEOIDs work).
| Place | Share of the tract |
|---|---|
| Waltham | 100% |
5 census tracts border Census Tract 3686: Tract 3684 ($131,250), Tract 3685 ($93,182), Tract 3687, Tract 3746 ($174,950) and Tract 3747 ($179,833). 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 3686?
The 2020-2024 American Community Survey puts Census Tract 3686's population at 5,688 (±693) in 2,492 households; the 2020 Census counted 5,856 residents and 2,706 housing units.
| Measure | Tract 3686 | Waltham |
|---|---|---|
| Total population | 5,688 ±693 | 64,902 |
| Households | 2,492 ±247 | 25,498 |
| Average household size | 2.28 ±0.23 | 2.23 |
| Housing units | 2,539 ±243 | 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 3686?
The median resident of Census Tract 3686 is 32.2 years old; 17.1% are under 18 and 10.1% are 65 or older. The largest group is non-Hispanic white residents at 58.9%, then Hispanic or Latino residents (of any race) at 25.3%. 15.5% of residents were born outside the United States.
| Measure | Tract 3686 | Waltham |
|---|---|---|
| Median age | 32.2 ±1.7 | 34.4 |
| Under 18 years | 17.1% ±3.7 pts | 13.6% |
| 65 years and over | 10.1% ±2.1 pts | 15.8% |
| Hispanic or Latino (any race) | 25.3% ±9.9 pts | 15.9% |
| White alone, not Hispanic | 58.9% ±9.6 pts | 57.6% |
| Black or African American alone, not Hispanic | 8.3% ±7.0 pts | 8.3% |
| Asian alone, not Hispanic | 1.8% ±2.6 pts | 12.6% |
| American Indian and Alaska Native alone, not Hispanic | 0.0% ±0.7 pts | 0.3% |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0% ±0.7 pts | 0.1% |
| Two or more races, not Hispanic | 5.3% ±4.6 pts | 4.3% |
| Some other race alone, not Hispanic | 0.4% ±0.7 pts | 0.9% |
| Born outside the United States | 15.5% ±5.8 pts | 26.3% |
| Speak a language other than English at home (age 5+) | 26.0% ±9.5 pts | 32.3% |
| Civilian veterans (age 18+) | 1.4% ±1.3 pts | 2.6% |
| With a disability | 10.3% ±3.5 pts | 10.7% |
| No health insurance coverage | 0.3% ±0.5 pts | 2.9% |
| High school graduate or higher (age 25+) | 92.3% ±4.5 pts | 93.3% |
| Bachelor's degree or higher (age 25+) | 55.3% ±10.0 pts | 57.3% |
| Graduate or professional degree (age 25+) | 27.8% ±8.9 pts | 27.9% |
| Lived in the same house a year earlier | 90.1% ±4.5 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 3686 earn?
Half of the 2,492 households in Census Tract 3686 earn less than $125,625 a year (±$16,661), against $130,847 across Middlesex County: 197th highest of the county's 350 tracts with a reliable estimate.
| Measure | Tract 3686 | Waltham |
|---|---|---|
| Median household income | $125,625 ±$16,661 | $120,216 |
| Mean household income | $138,503 ±$19,040 | $145,664 |
| Per capita income | $60,019 ±$9,410 | $58,449 |
| People below the poverty line | 4.4% ±3.6 pts | 9.4% |
| Children under 18 below the poverty line | 3.8% ±6.2 pts | 7.6% |
| Households receiving SNAP | 6.7% ±3.7 pts | 7.0% |
| Households with a computer | 98.5% ±1.8 pts | 95.6% |
| Households with a broadband subscription | 91.5% ±4.9 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 3686?
Owners occupy 36.9% of Census Tract 3686's occupied homes and renters 63.1%. The median owner-occupied home is valued at $586,400 by its owner (±$73,924). The median renter pays $2,122 a month including utilities, and 23.0% of renters pay 35% or more of their income on rent.
| Measure | Tract 3686 | Waltham |
|---|---|---|
| Median home value (owner-occupied) | $586,400 ±$73,924 | $748,700 |
| Median gross rent | $2,122 ±$129 | $2,268 |
| Renters paying 35% or more of income on rent | 23.0% ±9.8 pts | 35.7% |
| Median monthly owner costs, with a mortgage | $2,717 ±$161 | $3,076 |
| Owner-occupied homes | 36.9% ±8.4 pts | 49.7% |
| Renter-occupied homes | 63.1% ±8.4 pts | 50.3% |
| Housing units | 2,539 ±243 | 26,728 |
| Single-family detached homes | 16.7% ±6.0 pts | 37.0% |
| Mobile homes | 0.0% ±1.7 pts | 0.2% |
| Built 2020 or later | 0.0% ±1.7 pts | 1.1% |
| Built 2010 to 2019 | 1.1% ±1.4 pts | 6.4% |
| Built 1939 or earlier | 60.5% ±7.9 pts | 28.3% |
| Households with no vehicle | 3.7% ±2.7 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 3686 get to work?
51.2% of Census Tract 3686's workers drive alone and 28.4% work from home. The average trip to work takes 22.0 minutes.
| Measure | Tract 3686 | Waltham |
|---|---|---|
| In the labor force (age 16+) | 84.3% ±4.7 pts | 68.5% |
| Unemployment rate | 4.3% ±3.3 pts | 3.7% |
| Drove alone to work | 51.2% ±7.4 pts | 53.0% |
| Carpooled | 13.7% ±6.2 pts | 9.5% |
| Public transportation | 1.6% ±1.7 pts | 4.5% |
| Walked | 1.8% ±1.4 pts | 6.2% |
| Worked from home | 28.4% ±7.0 pts | 24.2% |
| Mean travel time to work | 22.0 min ±2.2 | 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 3686 compare with the other tracts in Middlesex County?
Among Middlesex County's tracts with a reliable estimate, Census Tract 3686 ranks as shown below (1 = highest).
| Measure | In Middlesex County | In Waltham |
|---|---|---|
| Population | 94th of 354 | 4th of 13 |
| Residents per square mile | 87th of 357 | 2nd of 13 |
| Median household income | 197th of 350 | 7th of 11 |
| Per capita income | 229th of 354 | 8th of 13 |
| Median home value | 269th of 350 | 12th of 13 |
| Median gross rent | 184th of 327 | 7th of 12 |
| Bachelor's degree or higher | 219th of 354 | 9th of 13 |
| Median age | 308th of 354 | 11th of 13 |
| Owner-occupied share | 284th of 351 | 11th of 13 |
The tracts next to it on Middlesex County's income ladder
| Tract | Rank | Median household income |
|---|---|---|
| Tract 3417 | 194th | $126,250±$45,828 · within the margin of this tract |
| Tract 3631.05 | 195th | $125,833±$38,250 · within the margin of this tract |
| Tract 3372.02 | 196th | $125,766±$32,460 · within the margin of this tract |
| Tract 3686 | 197th | $125,625±$16,661 |
| Tract 3336.01 | 198th | $125,278±$52,229 · within the margin of this tract |
| Tract 3398.02 | 199th | $125,000±$80,550 · within the margin of this tract |
| Tract 3398.03 | 200th | $124,756±$37,316 · 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 3686?
3 of the 18 figures for Census Tract 3686 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