Census tract · Middlesex County
Census Tract 3521.01, Middlesex County, Massachusetts
Census Tract 3521.01, GEOID 25017352101, in Middlesex County, Massachusetts, entirely within Cambridge. 3,401 residents in the ACS 2020-2024 5-year estimates (±400); the 2020 Census counted 4,271.
Residents, 2020-2024
3,401
±400 (90% margin)
2020 Census count: 4,271
Median household income
$123,077
±$40,823 (90% margin)
Middlesex County: $130,847
Median home value
$809,800
±$70,273 (90% margin)
Middlesex County: $727,800
Median gross rent
$3,453
±$288 (90% margin)
Middlesex County: $2,201
Where is Census Tract 3521.01?
Census Tract 3521.01 is one of 357 census tracts in Middlesex County, Massachusetts. It covers 0.16 square miles of land, 27,555 residents per square mile in 2020. Its GEOID, 25017352101, names it uniquely (how tract numbers and GEOIDs work).
| Place | Share of the tract |
|---|---|
| Cambridge | 100% |
7 census tracts border Census Tract 3521.01: Tract 3515 ($85,274), Tract 3521.02 ($175,110), Tract 3522 ($90,556), Tract 203.01 in Suffolk County ($133,333), Tract 203.05 in Suffolk County ($144,591), Tract 404.01 in Suffolk County ($168,883) and Tract 406 in Suffolk County ($142,941). 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 3521.01?
The 2020-2024 American Community Survey puts Census Tract 3521.01's population at 3,401 (±400) in 1,920 households; the 2020 Census counted 4,271 residents and 2,397 housing units.
| Measure | Tract 3521.01 | Cambridge |
|---|---|---|
| Total population | 3,401±400 | 118,796 |
| Households | 1,920±251 | 49,444 |
| Average household size | 1.60±0.11 | 2.05 |
| Housing units | 2,484±203 | 54,840 |
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 3521.01?
The median resident of Census Tract 3521.01 is 30.4 years old. The largest group is non-Hispanic white residents at 47.9%, then non-Hispanic Asian residents at 31.3%. 55.2% of residents were born outside the United States.
| Measure | Tract 3521.01 | Cambridge |
|---|---|---|
| Median age | 30.4±2.3 | 30.4 |
| Under 18 years | 5.5%±2.0 pts | 12.4% |
| 65 years and over | 3.9%±2.7 pts | 12.2% |
| Hispanic or Latino (any race) | 10.6%±3.9 pts | 8.8% |
| White alone, not Hispanic | 47.9%±7.0 pts | 53.8% |
| Black or African American alone, not Hispanic | 4.9%±2.8 pts | 10.3% |
| Asian alone, not Hispanic | 31.3%±7.2 pts | 20.2% |
| American Indian and Alaska Native alone, not Hispanic | 0.0%±1.2 pts | 0.1% |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0%±1.2 pts | 0.1% |
| Two or more races, not Hispanic | 4.9%±4.5 pts | 5.8% |
| Some other race alone, not Hispanic | 0.4%±0.7 pts | 0.9% |
| Born outside the United States | 55.2%±6.7 pts | 29.7% |
| Speak a language other than English at home (age 5+) | 56.4%±7.2 pts | 35.2% |
| Civilian veterans (age 18+) | 1.3%±1.3 pts | 1.6% |
| With a disability | 7.7%±3.5 pts | 7.5% |
| No health insurance coverage | 1.7%±1.2 pts | 1.7% |
| High school graduate or higher (age 25+) | 99.1%±1.1 pts | 96.0% |
| Bachelor's degree or higher (age 25+) | 86.9%±5.1 pts | 80.8% |
| Graduate or professional degree (age 25+) | 55.5%±7.9 pts | 51.2% |
| Lived in the same house a year earlier | 54.5%±7.9 pts | 74.5% |
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 3521.01 earn?
Half of the 1,920 households in Census Tract 3521.01 earn less than $123,077 a year (±$40,823), against $130,847 across Middlesex County: 207th highest of the county's 350 tracts with a reliable estimate. 12.0% of residents live below the poverty line.
| Measure | Tract 3521.01 | Cambridge |
|---|---|---|
| Median household income | $123,077±$40,823 | $130,748 |
| Mean household income | $152,689±$20,922 | $183,408 |
| Per capita income | $87,610±$9,952 | $78,723 |
| People below the poverty line | 12.0%±5.7 pts | 12.8% |
| Children under 18 below the poverty line | 9.8%±15.0 pts | 15.2% |
| Households receiving SNAP | 4.0%±2.9 pts | 8.4% |
| Households with a computer | 99.5%±0.7 pts | 98.5% |
| Households with a broadband subscription | 97.1%±1.9 pts | 94.8% |
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 3521.01?
Owners occupy 18.5% of Census Tract 3521.01's occupied homes and renters 81.5%. The median owner-occupied home is valued at $809,800 by its owner (±$70,273). The median renter pays $3,453 a month including utilities, and 39.3% of renters pay 35% or more of their income on rent.
| Measure | Tract 3521.01 | Cambridge |
|---|---|---|
| Median home value (owner-occupied) | $809,800±$70,273 | $1,092,100 |
| Median gross rent | $3,453±$288 | $2,787 |
| Renters paying 35% or more of income on rent | 39.3%±8.1 pts | 35.4% |
| Median monthly owner costs, with a mortgage | $3,855±$781 | $3,505 |
| Owner-occupied homes | 18.5%±7.3 pts | 33.5% |
| Renter-occupied homes | 81.5%±7.3 pts | 66.5% |
| Housing units | 2,484±203 | 54,840 |
| Single-family detached homes | 0.0%±1.7 pts | 9.9% |
| Mobile homes | 0.0%±1.7 pts | 0.1% |
| Built 2020 or later | 0.0%±1.7 pts | 2.2% |
| Built 2010 to 2019 | 44.2%±8.5 pts | 10.1% |
| Built 1939 or earlier | 1.0%±1.0 pts | 47.0% |
| Households with no vehicle | 34.9%±8.1 pts | 33.2% |
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 3521.01 get to work?
24.1% of Census Tract 3521.01's workers drive alone and 34.8% work from home. The average trip to work takes 33.6 minutes.
| Measure | Tract 3521.01 | Cambridge |
|---|---|---|
| In the labor force (age 16+) | 77.5%±5.6 pts | 69.6% |
| Unemployment rate | 0.9%±0.8 pts | 3.4% |
| Drove alone to work | 24.1%±8.5 pts | 19.7% |
| Carpooled | 5.9%±4.8 pts | 2.5% |
| Public transportation | 10.4%±4.5 pts | 18.0% |
| Walked | 20.4%±6.9 pts | 19.2% |
| Worked from home | 34.8%±8.1 pts | 30.8% |
| Mean travel time to work | 33.6 min±10.2 | 25.8 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 3521.01 compare with the other tracts in Middlesex County?
Among Middlesex County's tracts with a reliable estimate, Census Tract 3521.01 ranks as shown below (1 = highest).
| Measure | In Middlesex County | In Cambridge |
|---|---|---|
| Population | 269th of 354 | 15th of 33 |
| Residents per square mile | 18th of 357 | 10th of 33 |
| Median household income | 207th of 350 | 20th of 32 |
| Per capita income | 75th of 354 | 14th of 33 |
| Median home value | 133rd of 350 | 27th of 29 |
| Median gross rent | 9th of 327 | 2nd of 33 |
| Poverty rate | 70th of 223 | 14th of 30 |
| Bachelor's degree or higher | 23rd of 354 | 12th of 33 |
| Median age | 332nd of 354 | 23rd of 33 |
| Owner-occupied share | 336th of 351 | 26th of 30 |
The tracts next to it on Middlesex County's income ladder
| Tract | Rank | Median household income |
|---|---|---|
| Tract 3825 | 204th | $123,424±$43,219 · within the margin of this tract |
| Tract 3423.02 | 205th | $123,214±$18,094 · within the margin of this tract |
| Tract 3826.02 | 205th | $123,214±$35,743 · within the margin of this tract |
| Tract 3521.01 | 207th | $123,077±$40,823 |
| Tract 3526 | 208th | $123,050±$41,581 · within the margin of this tract |
| Tract 3641.02 | 209th | $122,966±$24,150 · within the margin of this tract |
| Tract 3331 | 210th | $122,917±$15,194 · 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 3521.01?
Every figure for Census Tract 3521.01 on this page has a coefficient of variation under 40%, the Census Bureau's threshold for a usable estimate.
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