Census-designated place · Connecticut
Cos Cob, Connecticut
Cos Cob, census-designated place, in Western Connecticut Planning Region, Connecticut. Cos Cob had 7,546 people in the ACS 2020-2024 5-year estimates (±960). GEOID 0917520.
Residents, 2020-2024
7,546
±960 (90% margin)
2020 Census count: 6,873
Median household income
$190,481
±$30,784 (90% margin)
Connecticut: $95,781
Median home value
$1,210,400
±$136,068 (90% margin)
Connecticut: $366,900
Median gross rent
$3,067
±$701 (90% margin)
Connecticut: $1,488
Where is Cos Cob and what county is it in?
Cos Cob is a census-designated place: an unincorporated community the Census Bureau draws for counting, with no city government of its own, in Western Connecticut Planning Region, Connecticut. It covers 2.2 square miles of land, 3,194 residents per square mile in 2020.
Cos Cob is in the Bridgeport-Stamford-Danbury, CT metropolitan statistical area, which takes in 2 counties (Census Bureau delineation, July 2023).
Cos Cob lies entirely within Greenwich, a town with its own local government (2020 census blocks).
Source: 2024 Gazetteer and 2020 place-by-county files, U.S. Census Bureau · Census reference files
How many people live in Cos Cob, and is it growing?
The 2020-2024 American Community Survey puts Cos Cob's population at 7,546 (±960). The 2020 Census counted 6,873 residents.
The Census Bureau publishes yearly population estimates for incorporated places only; Cos Cob is a census-designated place, so its figures come from the ACS and the 2020 Census.
| Measure | Cos Cob | Western Connecticut Planning Region | Change since 2015-2019 |
|---|---|---|---|
| Total population | 7,546 ±960 | 627,071 | no clear change |
| Households | 2,747 ±302 | 235,379 | no clear change |
| Average household size | 2.74 ±0.17 | 2.63 | no clear change |
| Housing units | 2,836 ±287 | 251,530 | no clear change |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); Census PEP Vintage 2025 (SUB-EST2025, CO-EST2025); 2020 Census P.L. 94-171 · Check it at data.census.gov
Who lives in Cos Cob?
The median resident of Cos Cob is 39.6 years old; 29.3% are under 18 and 15.5% are 65 or older. The largest group is non-Hispanic white residents at 64.4%, then Hispanic or Latino residents (of any race) at 15.0%. 25.2% of residents were born outside the United States.
| Measure | Cos Cob | Western Connecticut Planning Region | Change since 2015-2019 |
|---|---|---|---|
| Median age | 39.6 ±2.6 | 41.5 | no clear change |
| Under 18 years | 29.3% ±3.7 pts | 21.8% | – |
| 65 years and over | 15.5% ±4.1 pts | 17.4% | – |
| Male | 48.3% ±3.7 pts | 49.1% | – |
| Hispanic or Latino (any race) | 15.0% ±5.0 pts | 20.5% | no clear change |
| White alone, not Hispanic | 64.4% ±7.0 pts | 58.6% | −11.0 pts |
| Black or African American alone, not Hispanic | 3.1% ±3.2 pts | 9.3% | – |
| Asian alone, not Hispanic | 6.5% ±3.6 pts | 5.4% | no clear change |
| American Indian and Alaska Native alone, not Hispanic | 0.3% ±0.4 pts | 0.1% | – |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0% ±0.6 pts | 0.0% | – |
| Two or more races, not Hispanic | 10.4% ±7.1 pts | 4.8% | – |
| Some other race alone, not Hispanic | 0.2% ±0.4 pts | 1.2% | – |
| Born outside the United States | 25.2% ±6.2 pts | 23.8% | no clear change |
| Speak a language other than English at home (age 5+) | 26.6% ±7.6 pts | 29.7% | – |
| Civilian veterans (age 18+) | 3.1% ±2.0 pts | 3.1% | – |
| With a disability | 6.7% ±2.9 pts | 9.5% | – |
| No health insurance coverage | 5.3% ±3.1 pts | 7.2% | no clear change |
| High school graduate or higher (age 25+) | 95.3% ±3.5 pts | 91.7% | – |
| Bachelor's degree or higher (age 25+) | 70.2% ±7.6 pts | 55.5% | no clear change |
| Graduate or professional degree (age 25+) | 36.7% ±6.9 pts | 25.4% | – |
| Lived in the same house a year earlier | 89.3% ±6.4 pts | 89.2% | – |
| Moved from another state in the past year | 3.8% ±2.3 pts | 3.4% | – |
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 Cos Cob earn?
Half of Cos Cob's 2,747 households earn less than $190,481 a year (±$30,784), against $128,188 in Western Connecticut Planning Region and $95,781 in Connecticut. In 2015-2019 it was $183,835 in 2024 dollars; the margins of error cannot tell the two periods apart.
| Measure | Cos Cob | Western Connecticut Planning Region | Change since 2015-2019 |
|---|---|---|---|
| Median household income | $190,481 ±$30,784 | $128,188 | no clear change |
| Mean household income | $289,307 ±$49,794 | $214,668 | – |
| Per capita income | $104,168 ±$14,396 | $82,266 | no clear change |
| People below the poverty line | 5.6% ±3.8 pts | 7.5% | – |
| Children under 18 below the poverty line | 6.3% ±8.4 pts | 9.1% | – |
| Households receiving SNAP | 1.0% ±1.5 pts | 7.0% | – |
| Households with a computer | 99.5% ±0.8 pts | 96.6% | – |
| Households with a broadband subscription | 99.3% ±0.8 pts | 94.7% | – |
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 Cos Cob?
Owners occupy 66.7% of Cos Cob's occupied homes and renters 33.3%. The median owner-occupied home is valued at $1,210,400 by its owner (±$136,068). The median renter pays $3,067 a month including utilities, and 54.0% of renters pay 35% or more of their income on rent.
| Measure | Cos Cob | Western Connecticut Planning Region | Change since 2015-2019 |
|---|---|---|---|
| Median home value (owner-occupied) | $1,210,400 ±$136,068 | $652,900 | no clear change |
| Median gross rent | $3,067 ±$701 | $2,110 | no clear change |
| Renters paying 35% or more of income on rent | 54.0% ±14.5 pts | 43.4% | +19.1 pts |
| Median monthly owner costs, with a mortgage | $4,000 or more | $3,494 | – |
| Owner-occupied homes | 66.7% ±7.9 pts | 66.4% | no clear change |
| Renter-occupied homes | 33.3% ±7.9 pts | 33.6% | – |
| Housing units | 2,836 ±287 | 251,530 | no clear change |
| Homeowner vacancy rate | 0.0% ±2.3 pts | 1.1% | – |
| Rental vacancy rate | 0.0% ±4.5 pts | 3.8% | – |
| Single-family detached homes | 61.2% ±7.5 pts | 57.3% | – |
| Mobile homes | 0.2% ±0.3 pts | 0.4% | – |
| Built 2020 or later | 0.0% ±1.5 pts | 1.0% | – |
| Built 2010 to 2019 | 9.2% ±4.4 pts | 8.2% | – |
| Built 1939 or earlier | 28.1% ±6.3 pts | 16.3% | – |
| Households with no vehicle | 3.0% ±2.6 pts | 6.2% | – |
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 Cos Cob work and get to work?
52.0% of Cos Cob's workers drive alone and 30.0% work from home. The average trip to work takes 28.9 minutes. The unemployment rate in 2020-2024 averaged 6.7%.
| Measure | Cos Cob | Western Connecticut Planning Region | Change since 2015-2019 |
|---|---|---|---|
| In the labor force (age 16+) | 70.7% ±4.8 pts | 68.3% | – |
| Unemployment rate | 6.7% ±3.0 pts | 5.3% | no clear change |
| Drove alone to work | 52.0% ±6.7 pts | 59.3% | – |
| Carpooled | 4.5% ±3.1 pts | 8.1% | – |
| Public transportation | 9.6% ±3.8 pts | 7.0% | – |
| Walked | 2.9% ±2.8 pts | 2.5% | – |
| Worked from home | 30.0% ±6.4 pts | 21.5% | +19.9 pts |
| Mean travel time to work | 28.9 min ±3.1 | 30.8 min | −5.4 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
What census tracts are in Cos Cob?
2 census tracts lie mostly in Cos Cob (2020 census blocks). Their median household incomes run from $205,938 (Tract 108) to $224,242 (Tract 102.02).
| Tract | Residents, 2020-2024 | Median household income |
|---|---|---|
| Tract 108Western Connecticut Planning Region | 3,488 | $205,938 |
| Tract 102.02Western Connecticut Planning Region | 5,793 | $224,242 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 block assignment files (tract share = share of the tract's census blocks in Cos Cob) · Census block assignment files
How does Cos Cob compare with other places in Connecticut?
Cos Cob ranks 28th of 294 places in Connecticut with 1,000 or more residents and a reliable estimate, by median household income.
| Measure | Rank | Of |
|---|---|---|
| Population (ACS 2020-2024) | 133rd | 303 |
| Residents per square mile | 30th | 303 |
| Median household income | 28th | 294 |
| Per capita income | 31st | 303 |
| Median home value | 17th | 300 |
| Median gross rent | 16th | 266 |
| Bachelor's degree or higher | 42nd | 297 |
| Median age | 246th | 301 |
| Owner-occupied share | 233rd | 300 |
| Work from home | 39th | 279 |
| Travel time to work | 118th | 302 |
Cos Cob's figures with every place in Connecticut (CSV)
Every place in Connecticut, sortable · Compare Cos Cob with other places
Source: PlainCities ranks computed from the American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) and PEP Vintage 2025 · How ranks are computed
How reliable are the figures for Cos Cob?
15 of the 57 figures for Cos Cob 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.
The American Community Survey samples about one household in eight over five years, so every figure is an estimate with a 90% margin of error (shown under each value). A ring marks an estimate whose coefficient of variation is over 40%. A change is called only when the gap between the two periods is larger than their combined 90% margin (the square root of the sum of the two squared margins), the Census Bureau's test. 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 · ACS technical documentation
How these figures are made: methodology and release checks · reading a margin of error · every state · corrections
Not on this page: crime, weather and schools for Cos Cob are other agencies' records. Crime: the FBI's Crime Data Explorer · climate: NOAA's U.S. Climate Normals · schools: the National Center for Education Statistics' school search.