County · New Jersey
Mercer County, New Jersey
Mercer County, New Jersey. Mercer County had 399,289 residents in 2025 by the Census Bureau's estimate, up 3.1% since 2020, in line with New Jersey (+2.8%). It holds 25 places (5 cities, villages and boroughs, 7 towns and townships and 13 census-designated) and 84 census tracts. GEOID 34021.
Mercer County is the county of the Trenton-Princeton, NJ metropolitan statistical area (the Census Bureau's July 2023 delineation).
Residents, July 2025 estimate
399,289
Census Bureau estimate (no margin published)
2020 Census count: 387,340 · ACS 2020-2024: 385,864
Median household income
$100,645
±$2,565 (90% margin)
New Jersey: $103,556
Median home value
$377,700
±$6,110 (90% margin)
New Jersey: $454,400
Median gross rent
$1,623
±$34 (90% margin)
New Jersey: $1,720
How many people live in Mercer County, and is it growing?
The 2020 Census counted 387,340 residents in Mercer County. The Census Bureau estimates 399,289 for July 1, 2025, up 3.1% since 2020, in line with New Jersey (+2.8%). The 2020-2024 American Community Survey puts the population at 385,864 over 224 square miles of land.
| Measure | Mercer County | New Jersey | Change since 2015-2019 |
|---|---|---|---|
| Total population | 385,864 | 9,343,809 | +17,942 |
| Households | 144,114±834 | 3,507,701 | +14,178 |
| Average household size | 2.56±0.01 | 2.62 | −0.14 |
| Housing units | 151,138±116 | 3,791,354 | +6,283 |
Mercer County's population since 2000
From 350,761 in 2000 to 399,289 in 2025: up 13.8%. The 2000, 2010 and 2020 figures are census counts. The 2005 figure is the Census Bureau's intercensal estimate, revised to fit the 2000 and 2010 counts and drawn on 2010 boundaries; 2015 and 2025 are July 1 estimates made from the census before them.
Source: The 2000, 2010 and 2020 Census counts and the Census Bureau's population estimates (intercensal 2000-2010, Vintage 2020, Vintage 2025) · Census population estimates
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); PEP Vintage 2025 (CO-EST2025); 2020 Census · Check it at data.census.gov
What cities and towns are in Mercer County?
Mercer County holds 25 places: 5 cities, villages and boroughs (incorporated places), 7 towns and townships (county subdivisions with their own government) and 13 census-designated places. The largest is Hamilton Township, Mercer County with 94,157 residents (2025 estimate). Places that cross a county line are listed with the share of their 2020 residents who live in this county.
| Hamilton Township, Mercer County | 92,297 | $100,771 |
|---|---|---|
| Trenton | 90,871 | $52,537 |
| Ewing Township | 37,264 | $91,267 |
| Lawrence Township, Mercer County | 33,077 | $130,142 |
| Princeton | 30,681 | $192,079 |
| East Windsor Township | 30,045 | $105,208 |
| West Windsor Township | 29,518 | $197,190 |
| Hopewell Township, Mercer County | 17,491 | $178,167 |
| Robbinsville Township | 15,476 | $169,450 |
| Mercerville | 13,447 | $128,277 |
| Hamilton Square | 12,679 | $138,162 |
| White Horse | 9,791 | $105,758 |
| Twin Rivers | 7,787 | $100,833 |
| Yardville | 6,965 | $103,274 |
| Hightstown | 5,900 | $108,987 |
| Lawrenceville | 3,751 | $122,614 |
| The College of New JerseyGEOID 3472580 | 3,701 | not published |
| Robbinsville Center | 3,164 | $134,388 |
| GrovevilleGEOID 3428620 | 3,106 | $112,188 |
| Pennington | 2,802 | $192,586 |
| Princeton Junction | 2,475 | $224,732 |
| Hopewell | 1,918 | $145,114 |
| TitusvilleGEOID 3473050 | 633 | $120,234 |
| Washington CrossingGEOID 3477330 | 371 | $186,458 |
| WindsorGEOID 3481620 | 330 | not published |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 place-by-county parts · Check it at data.census.gov
Who lives in Mercer County?
The median resident of Mercer County is 39.5 years old; 22.0% are under 18 and 16.0% are 65 or older. The largest group is non-Hispanic white residents at 42.7%, then Hispanic or Latino residents (of any race) at 23.1%. 27.0% of residents were born outside the United States.
| Measure | Mercer County | New Jersey | Change since 2015-2019 |
|---|---|---|---|
| Median age | 39.5±0.2 | 40.1 | +0.7 |
| Under 18 years | 22.0% | 21.8% | – |
| 65 years and over | 16.0%±0.1 pts | 17.2% | – |
| Hispanic or Latino (any race) | 23.1% | 22.5% | +5.6 pts |
| White alone, not Hispanic | 42.7%±0.2 pts | 50.9% | −7.0 pts |
| Black or African American alone, not Hispanic | 17.9%±0.3 pts | 12.2% | −1.9 pts |
| Asian alone, not Hispanic | 12.3%±0.2 pts | 10.0% | +1.2 pts |
| American Indian and Alaska Native alone, not Hispanic | 0.1%±0.1 pts | 0.1% | – |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0%±0.1 pts | 0.0% | – |
| Two or more races, not Hispanic | 3.4%±0.4 pts | 3.5% | – |
| Some other race alone, not Hispanic | 0.5%±0.1 pts | 0.8% | – |
| Born outside the United States | 27.0%±0.9 pts | 23.9% | +4.1 pts |
| Speak a language other than English at home (age 5+) | 35.7%±0.8 pts | 33.1% | – |
| Civilian veterans (age 18+) | 3.4%±0.3 pts | 3.7% | – |
| With a disability | 10.7%±0.5 pts | 10.8% | – |
| No health insurance coverage | 7.9%±0.5 pts | 7.5% | no clear change |
| High school graduate or higher (age 25+) | 89.4%±0.6 pts | 90.7% | – |
| Bachelor's degree or higher (age 25+) | 45.4%±0.8 pts | 43.6% | +2.8 pts |
| Graduate or professional degree (age 25+) | 21.2%±0.6 pts | 17.6% | – |
| Moved from another state in the past year | 2.6%±0.3 pts | 1.8% | – |
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 Mercer County earn?
Half of Mercer County's 144,114 households earn less than $100,645 a year (±$2,565), against $103,556 in New Jersey. In 2015-2019 it was $99,756 in 2024 dollars; the margins of error cannot tell the two periods apart. 10.3% of residents live below the poverty line.
| Measure | Mercer County | New Jersey | Change since 2015-2019 |
|---|---|---|---|
| Median household income | $100,645±$2,565 | $103,556 | no clear change |
| Mean household income | $142,368±$3,598 | $143,363 | – |
| Per capita income | $53,765±$1,398 | $54,253 | no clear change |
| People below the poverty line | 10.3%±0.8 pts | 9.7% | −1.3 pts |
| Children under 18 below the poverty line | 13.2%±2.0 pts | 13.0% | no clear change |
| Households receiving SNAP | 9.3%±0.7 pts | 9.1% | – |
| Households with a broadband subscription | 91.4%±0.8 pts | 92.8% | – |
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 Mercer County?
Owners occupy 62.2% of Mercer County's occupied homes and renters 37.8%. The median owner-occupied home is valued at $377,700 by its owner (±$6,110). The median renter pays $1,623 a month including utilities, and 41.3% of renters pay 35% or more of their income on rent.
| Measure | Mercer County | New Jersey | Change since 2015-2019 |
|---|---|---|---|
| Median home value (owner-occupied) | $377,700±$6,110 | $454,400 | +$19,445 |
| Median gross rent | $1,623±$34 | $1,720 | +$65 |
| Renters paying 35% or more of income on rent | 41.3%±2.3 pts | 42.7% | no clear change |
| Median monthly owner costs, with a mortgage | $2,615±$56 | $2,829 | – |
| Owner-occupied homes | 62.2%±1.2 pts | 63.8% | no clear change |
| Housing units | 151,138±116 | 3,791,354 | +6,283 |
| Homeowner vacancy rate | 0.4%±0.2 pts | 0.7% | – |
| Rental vacancy rate | 2.9%±0.8 pts | 3.5% | – |
| Single-family detached homes | 47.5%±1.0 pts | 52.6% | – |
| Mobile homes | 0.5%±0.2 pts | 0.9% | – |
| Built 2020 or later | 0.9%±0.2 pts | 1.1% | – |
| Built 1939 or earlier | 17.9%±0.8 pts | 17.4% | – |
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 many new homes is Mercer County building?
Builders took permits for 1,164 new housing units across Mercer County in 2025 (805 single-family), 2.9 per 1,000 residents.
Source: Building Permits Survey, annual county files 2019-2025, U.S. Census Bureau · Census Building Permits Survey
How do people in Mercer County get to work?
60.2% of Mercer County's workers drive alone and 19.5% work from home. The average trip to work takes 27.1 minutes. The unemployment rate in 2020-2024 averaged 6.3%.
| Measure | Mercer County | New Jersey | Change since 2015-2019 |
|---|---|---|---|
| In the labor force (age 16+) | 65.3%±0.8 pts | 66.4% | – |
| Unemployment rate | 6.3%±0.6 pts | 6.3% | no clear change |
| Drove alone to work | 60.2%±1.1 pts | 62.2% | – |
| Carpooled | 8.7%±0.7 pts | 7.7% | – |
| Public transportation | 4.6%±0.4 pts | 8.1% | – |
| Walked | 3.6%±0.4 pts | 2.6% | – |
| Worked from home | 19.5%±0.9 pts | 16.8% | +14.4 pts |
| Mean travel time to work | 27.1 min±0.5 | 30.5 min | −1.2 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
What are Mercer County's census tracts?
Mercer County is divided into 84 census tracts. Among those with a reliable estimate, median household income runs from $24,659 (Tract 10) to $250,000 or more (Tract 43.15).
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) · Check it at data.census.gov
How does Mercer County compare with New Jersey's other counties?
| Measure | Rank |
|---|---|
| Population | 12th of 21 |
| Growth 2020-2025 | 7th of 21 |
| Residents per square mile | 8th of 21 |
| Median household income | 12th of 21 |
| Median home value | 13th of 21 |
| Median gross rent | 11th of 21 |
| Poverty rate | 9th of 21 |
| Bachelor's degree or higher | 8th of 21 |
| Median age | 14th of 21 |
Source: PlainCities ranks 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 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 Mercer County 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.