Census tract · Mercer County
Census Tract 40, Mercer County, New Jersey
Census Tract 40, GEOID 34021004000, in Mercer County, New Jersey, entirely within Princeton. 5,705 residents in the ACS 2020-2024 5-year estimates (±705); the 2020 Census counted 5,686.
Residents, 2020-2024
5,705
±705 (90% margin)
2020 Census count: 5,686
Median household income
$110,375
±$20,450 (90% margin)
Mercer County: $100,645
Median home value
$912,400
±$93,590 (90% margin)
Mercer County: $377,700
Median gross rent
$2,344
±$322 (90% margin)
Mercer County: $1,623
Where is Census Tract 40?
Census Tract 40 is one of 84 census tracts in Mercer County, New Jersey. It covers 0.68 square miles of land, 8,424 residents per square mile in 2020. Its GEOID, 34021004000, names it uniquely (how tract numbers and GEOIDs work).
| Place | Share of the tract |
|---|---|
| Princeton | 100% |
4 census tracts border Census Tract 40: Tract 42.05 ($250,000 or more), Tract 42.06 ($181,528), Tract 45.01 ($197,434) and Tract 45.02. 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 40?
The 2020-2024 American Community Survey puts Census Tract 40's population at 5,705 (±705) in 2,396 households; the 2020 Census counted 5,686 residents and 2,761 housing units.
| Measure | Tract 40 | Princeton |
|---|---|---|
| Total population | 5,705 ±705 | 30,756 |
| Households | 2,396 ±174 | 9,300 |
| Average household size | 2.32 ±0.23 | 2.54 |
| Housing units | 2,489 ±182 | 9,906 |
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 40?
The median resident of Census Tract 40 is 35.7 years old; 19.6% are under 18 and 10.9% are 65 or older. The largest group is non-Hispanic white residents at 65.4%, then non-Hispanic Asian residents at 12.1%. 33.2% of residents were born outside the United States.
| Measure | Tract 40 | Princeton |
|---|---|---|
| Median age | 35.7 ±4.5 | 28.5 |
| Under 18 years | 19.6% ±5.4 pts | 18.8% |
| 65 years and over | 10.9% ±2.2 pts | 13.0% |
| Hispanic or Latino (any race) | 11.5% ±4.7 pts | 8.0% |
| White alone, not Hispanic | 65.4% ±8.0 pts | 57.8% |
| Black or African American alone, not Hispanic | 5.3% ±1.8 pts | 6.1% |
| Asian alone, not Hispanic | 12.1% ±3.7 pts | 21.5% |
| 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 | 0.0% |
| Two or more races, not Hispanic | 5.8% ±3.3 pts | 5.4% |
| Some other race alone, not Hispanic | 0.0% ±0.8 pts | 0.8% |
| Born outside the United States | 33.2% ±8.2 pts | 30.9% |
| Speak a language other than English at home (age 5+) | 32.5% ±8.8 pts | 35.2% |
| Civilian veterans (age 18+) | 0.7% ±0.9 pts | 1.6% |
| With a disability | 6.6% ±2.8 pts | 6.6% |
| No health insurance coverage | 1.7% ±2.3 pts | 1.8% |
| High school graduate or higher (age 25+) | 97.1% ±2.4 pts | 97.7% |
| Bachelor's degree or higher (age 25+) | 79.8% ±7.0 pts | 84.7% |
| Graduate or professional degree (age 25+) | 55.1% ±11.0 pts | 56.8% |
| Lived in the same house a year earlier | 72.4% ±7.3 pts | 77.0% |
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 40 earn?
Half of the 2,396 households in Census Tract 40 earn less than $110,375 a year (±$20,450), against $100,645 across Mercer County: 34th highest of the county's 81 tracts with a reliable estimate. 9.1% of residents live below the poverty line.
| Measure | Tract 40 | Princeton |
|---|---|---|
| Median household income | $110,375 ±$20,450 | $192,079 |
| Mean household income | $189,440 ±$34,373 | $275,137 |
| Per capita income | $82,235 ±$11,511 | $87,301 |
| People below the poverty line | 9.1% ±3.4 pts | 6.1% |
| Children under 18 below the poverty line | 3.4% ±4.1 pts | 3.7% |
| Households receiving SNAP | 3.0% ±2.3 pts | 2.0% |
| Households with a computer | 99.0% ±1.5 pts | 99.4% |
| Households with a broadband subscription | 93.4% ±7.2 pts | 93.4% |
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 40?
Owners occupy 42.5% of Census Tract 40's occupied homes and renters 57.5%. The median owner-occupied home is valued at $912,400 by its owner (±$93,590). The median renter pays $2,344 a month including utilities, and 48.5% of renters pay 35% or more of their income on rent.
| Measure | Tract 40 | Princeton |
|---|---|---|
| Median home value (owner-occupied) | $912,400 ±$93,590 | $1,050,600 |
| Median gross rent | $2,344 ±$322 | $2,636 |
| Renters paying 35% or more of income on rent | 48.5% ±10.6 pts | 30.7% |
| Median monthly owner costs, with a mortgage | $3,598 ±$449 | $4,000 or more |
| Owner-occupied homes | 42.5% ±7.8 pts | 55.4% |
| Renter-occupied homes | 57.5% ±7.8 pts | 44.6% |
| Housing units | 2,489 ±182 | 9,906 |
| Single-family detached homes | 32.4% ±9.2 pts | 54.2% |
| Mobile homes | 0.0% ±1.8 pts | 0.0% |
| Built 2020 or later | 0.0% ±1.8 pts | 2.7% |
| Built 2010 to 2019 | 14.6% ±5.2 pts | 9.8% |
| Built 1939 or earlier | 43.4% ±7.0 pts | 23.3% |
| Households with no vehicle | 22.0% ±6.5 pts | 11.9% |
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 40 get to work?
29.9% of Census Tract 40's workers drive alone and 28.0% work from home. The average trip to work takes 27.6 minutes.
| Measure | Tract 40 | Princeton |
|---|---|---|
| In the labor force (age 16+) | 71.5% ±5.1 pts | 63.3% |
| Unemployment rate | 2.3% ±1.9 pts | 4.3% |
| Drove alone to work | 29.9% ±10.4 pts | 32.1% |
| Carpooled | 2.9% ±2.1 pts | 2.1% |
| Public transportation | 7.0% ±3.0 pts | 7.7% |
| Walked | 23.8% ±9.8 pts | 19.9% |
| Worked from home | 28.0% ±11.6 pts | 32.7% |
| Mean travel time to work | 27.6 min ±4.7 | 24.2 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 40 compare with the other tracts in Mercer County?
Among Mercer County's tracts with a reliable estimate, Census Tract 40 ranks as shown below (1 = highest).
| Measure | In Mercer County | In Princeton |
|---|---|---|
| Population | 24th of 84 | 3rd of 7 |
| Residents per square mile | 20th of 84 | 2nd of 7 |
| Median household income | 34th of 81 | 6th of 6 |
| Per capita income | 13th of 83 | 5th of 7 |
| Median home value | 6th of 76 | 6th of 7 |
| Median gross rent | 10th of 76 | 5th of 6 |
| Poverty rate | 30th of 47 | 2nd of 4 |
| Bachelor's degree or higher | 10th of 79 | 6th of 7 |
| Median age | 65th of 84 | 5th of 7 |
| Owner-occupied share | 65th of 81 | 7th of 7 |
The tracts next to it on Mercer County's income ladder
| Tract | Rank | Median household income |
|---|---|---|
| Tract 32.01 | 31st | $117,179±$26,307 · within the margin of this tract |
| Tract 43.13 | 32nd | $117,000±$50,310 · within the margin of this tract |
| Tract 43.11 | 33rd | $114,950±$28,621 · within the margin of this tract |
| Tract 40 | 34th | $110,375±$20,450 |
| Tract 44.03 | 35th | $108,987±$15,365 · within the margin of this tract |
| Tract 44.07 | 36th | $107,778±$32,688 · within the margin of this tract |
| Tract 37.03 | 37th | $104,715±$14,538 · 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 40?
Every figure for Census Tract 40 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