Mercer County, New Jersey Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 12th-largest in New Jersey
The population of Mercer County, New Jersey is 383,286 as of the 2023 American Community Survey, making it the 12th-largest county in New Jersey. The median household income is $96,333, the median home value is $351,000, and the median age is 39.2.
The population of Mercer County has grown 6.6% since 2010 (367,717 → 392,138), a +0.46% annualized rate.
383,286
Population
+0.46%
Annual growth
1707
People / sq mi
$96,333
Median Income
$351,000
Median Home Value
Mercer County covers 224 sq mi of land at 1707.4 people per square mile.
About Mercer County, NJ
What distinguishes Mercer County is density: among the most densely settled of US counties, around 1,707 people per square mile. With 383,286 residents, Mercer County is a county in New Jersey. It ranks #12 among counties in New Jersey by population.
Income is a real outlier — the median household pulls in $96,333, putting Mercer County near the top of US counties. The poverty rate is 7.5%, below the national 12.4%. Home values run above average at $351,000, with typical rent around $1,515.
Mercer County is among the best-educated US counties: 44.9% of adults 25 and older hold a bachelor’s degree, above the national 35.0%. Working from home is common here: 17.8% of workers do so, above the national 14.0%, and the average commute runs about 28 minutes each way.
That density explains much of the rest of the profile in Mercer County: denser places lean toward renting, shorter commutes by transit, and a younger working-age mix.
Mercer County Population History (2010-2024)
The county of Mercer County had a population of 367,717 in 2010 and 392,138 in 2024, a 6.6% growth over 14 years. The peak was 392,138 in 2024. Average annual growth rate: 0.47%.
392,138
Population (2024)
367,717
Population (2010)
392,138
Peak (2024)
0.47%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 367,717 |
| 2011 | 367,407 |
| 2012 | 368,628 |
| 2013 | 369,534 |
| 2014 | 369,031 |
| 2015 | 368,266 |
| 2016 | 367,929 |
| 2017 | 368,489 |
| 2018 | 368,720 |
| 2019 | 368,047 |
| 2020 | 386,492 |
| 2021 | 382,231 |
| 2022 | 382,165 |
| 2023 | 386,296 |
| 2024 | 392,138 |
Race & Ethnicity
| White | 49.8% |
| Black or African American | 19.2% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 1.4% |
| Two or More Races | 0.0% |
Age & Sex
39.2
Median Age
50.6%
Female
49.4%
Male
15.7%
Age 65+
Age Distribution
Children (under 15): 18.0% · Seniors (65+): 15.7%
Income & Poverty
| Median household income | $96,333$-4,717 vs state |
| Mean household income | $138,732 |
| Per-capita income | $52,101 |
| Poverty rate | 7.5%+0.5% vs state |
| Unemployment rate | 3.9% |
| Employment-to-population | 60.2% |
Top Industries by Employment
The largest employment sector in Mercer County is professional & business services, accounting for 26.7% of workers.
How residents commute
5.2%
Drive alone
3.5%
Carpool
61.5%
Public transit
17.8%
Work from home
27.6 min
Avg commute
Housing
$351,000$-76,600 vs state
Median home value
$1,515
Median rent
61.9%
Homeownership rate
150,600
Total housing units
93.9%
Occupied
6.1%
Vacant
38.1%
Renter-occupied
Social & access
92.4%
With health insurance
95.1%
With broadband internet
21.6%
Foreign-born
3.6%
Veterans (18+)
10.1%
With a disability
65.2%
Speak language other than English at home
Education
89.9%
High School+
44.9%
Bachelor's+
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County rankings
Common questions about Mercer County, NJ
Frequently Asked Questions
Mercer County, New Jersey has a population of 383,286 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 12th-largest county in New Jersey. Population density is 1707 people per square mile.
The population of Mercer County has grown 6.6% since 2010 (367,717 → 392,138), a +0.46% annualized rate.
The median household income in Mercer County, New Jersey is $96,333, with mean (average) household income of $138,732 and per-capita income of $52,101. 7.5% of residents live below the federal poverty level.
In Mercer County, the largest racial and ethnic groups are White (49.8%), Black or African American (19.2%), Hispanic or Latino (1.4%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Mercer County, New Jersey is 39.2 years. Residents are 50.6% female and 49.4% male.
The median home value in Mercer County is $351,000 and median monthly rent is $1,515. 61.9% of occupied housing units are owner-occupied. The county has 150,600 total housing units, 6.1% of which are vacant.
The largest employment sector in Mercer County, New Jersey is professional, scientific, and management services, employing 26.7% of workers. The unemployment rate is 3.9%.
Newark is among the largest cities associated with Mercer County, New Jersey, with a population of 307,188.
Mercer County, NJ Climate
Mercer County, NJ has an average annual temperature of 11.7°C (53°F) and receives about 1203 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
11.7°C
Avg Temp
1203
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -1° / 30° | 94 mm |
| February | 0° / 33° | 73 mm |
| March | 5° / 41° | 101 mm |
| April | 11° / 51° | 101 mm |
| May | 16° / 61° | 112 mm |
| June | 21° / 70° | 101 mm |
| July | 24° / 75° | 122 mm |
| August | 23° / 73° | 115 mm |
| September | 19° / 66° | 105 mm |
| October | 13° / 55° | 88 mm |
| November | 7° / 45° | 97 mm |
| December | 2° / 36° | 94 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit Mercer County, NJ
The most comfortable months to visit Mercer County, NJ are typically June, September and August, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 30°C high). The coldest is January (near -6°C low). July is usually the wettest month.
Where to stay near Mercer County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.