Demographics of Mercer County, New Jersey

Mercer County, New Jersey had 399,289 people on July 1, 2025, by the Census Bureau’s estimate: +12,855 since July 2020. Age, income, poverty, housing and origin below come from the American Community Survey, averaged over 2020–2024, each with its margin of error.

Mercer County, in four figures

399,289
Population: July 1, 2025, Vintage 2025 estimate.; +3.3%
Change since July 2020: +12,855 people.; 39.5 ±0.2
Median age: ACS 2020–⁠2024.; $100,645 ±$2,565
Median household income: ACS 2020–⁠2024, in 2024 dollars.

Population, year by year

July 1 estimates from the Census Bureau’s Vintage 2025. Each year's change is births less deaths, net moves from abroad and net moves from elsewhere in the country, with the Bureau's small residual. The 2020 row's components run 3 months, from the April census to July 1.

Mercer County, New Jersey's population grew 3.3% from July 2020 to July 2025, against +3.1% nationally

The July 1 estimate of Mercer County, New Jersey's resident population and the nation's, each year of the Census Bureau's Vintage 2025, as a share of its July 2020 level (= 100).

U.S. Census Bureau — Census Bureau population estimates — counties and Puerto Rico municipios, with components of change

About this chart

The figures

Mercer County, New Jersey's population grew 3.3% from July 2020 to July 2025, against +3.1% nationally. The July 1 estimate of Mercer County, New Jersey's resident population and the nation's, each year of the Census Bureau's Vintage 2025, as a share of its July 2020 level (= 100).
July 1	Population	Index	United States
2020	386,434	100.0	100.0
2021	382,139	98.9	100.2
2022	387,024	100.2	100.7
2023	391,369	101.3	101.6
2024	397,329	102.8	102.5
2025	399,289	103.3	103.1

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Population of Mercer County, New Jersey on July 1 of each year, Vintage 2025
July 1	Population	Change	Births less deaths	From abroad	From elsewhere in the country
2020	386,434	−900	−313	+30	−638
2021	382,139	−4,295	+541	+817	−5,423
2022	387,024	+4,885	+709	+4,527	−151
2023	391,369	+4,345	+1,053	+6,188	−2,938
2024	397,329	+5,960	+1,048	+7,693	−2,811
2025	399,289	+1,960	+1,082	+3,089	−2,240

Age, 2020–2024

The median age is 39.5 ±0.2: for men 38.0 ±0.3 and for women 40.8 ±0.3. Shares are of everyone the survey counts, in the Bureau’s sex-by-age table (B01001).

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People in Mercer County by age, ACS 2020–2024
Age	People	Share	New Jersey	United States
Under 5	21,584 ±28	5.6% ±<0.1	5.6% ±<0.1	5.6% ±<0.1
5 to 17	63,244 ±1,607	16.4% ±0.4	16.2% ±0.1	16.3% ±<0.1
18 to 24	39,425 ±1,294	10.2% ±0.3	8.4% ±0.1	9.1% ±<0.1
25 to 44	98,143 ±1,557	25.4% ±0.4	26.2% ±0.1	26.9% ±<0.1
45 to 64	101,911 ±1,541	26.4% ±0.4	26.5% ±0.1	24.8% ±<0.1
65 and over	61,557 ±1,704	16.0% ±0.4	17.2% ±0.1	17.2% ±<0.1

Income and poverty, 2020–2024

Median household income is $100,645 ±$2,565, and income per person $53,765 ±$1,398, in 2024 dollars. The median is $103,556 ±$513 in New Jersey and $80,734 ±$166 in the United States.

Households by income

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Households in Mercer County by income, ACS 2020–2024
Household income	Households	Share	New Jersey	United States
Under $25,000	18,010 ±1,315	12.5% ±0.9	11.6% ±0.2	14.6% ±<0.1
$25,000 to $49,999	20,025 ±1,491	13.9% ±1.0	12.8% ±0.2	16.7% ±<0.1
$50,000 to $74,999	17,844 ±1,260	12.4% ±0.9	12.8% ±0.2	15.5% ±<0.1
$75,000 to $99,999	15,763 ±1,241	10.9% ±0.9	11.3% ±0.2	12.6% ±<0.1
$100,000 to $149,999	24,944 ±1,444	17.3% ±1.0	18.1% ±0.2	17.5% ±<0.1
$150,000 to $199,999	16,895 ±1,226	11.7% ±0.8	11.8% ±0.2	9.6% ±<0.1
$200,000 or more	30,633 ±1,207	21.3% ±0.8	21.6% ±0.2	13.4% ±0.1

Poverty by age

The poverty rate is the share of people whose family income is below the federal threshold for their family’s size, of everyone for whom the Bureau determines it (B17020).

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Poverty rate in Mercer County by age, ACS 2020–2024
Age	Below poverty	Rate	New Jersey	United States
All ages	37,849 ±3,114	10.3% ±0.8	9.7% ±0.2	12.5% ±0.1
Under 18	11,034 ±1,414	13.2% ±1.6	13.0% ±0.3	16.1% ±0.1
18 to 59	18,771 ±1,784	9.4% ±0.9	8.6% ±0.2	11.6% ±0.1
60 and over	8,044 ±874	9.4% ±1.0	9.3% ±0.2	11.0% ±<0.1

Housing, 2020–2024

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Housing in Mercer County, ACS 2020–2024
Measure	Mercer County	New Jersey	United States
Housing units	151,138 ±116	3,791,354 ±469	143,775,355 ±10,234
Occupied	95.4% ±0.5	92.5% ±0.1	89.9% ±0.1
Vacant	4.6% ±0.5	7.5% ±0.1	10.1% ±0.1
Owner occupied	62.2% ±1.1	63.8% ±0.3	65.2% ±0.3
Renter occupied	37.8% ±1.2	36.2% ±0.2	34.8% ±0.1
Median home value	$377,700 ±$6,110	$454,400 ±$1,150	$332,700 ±$236
Median gross rent	$1,623 ±$34	$1,720 ±$7	$1,413 ±$2
Median year built	1969 ±1	1970 ±1	1980 ±1

Occupied and vacant are shares of all housing units; owner and renter occupied are shares of occupied units. Value and rent are medians in 2024 dollars.

Origin and place of birth, 2020–2024

Hispanic or Latino origin is not a race in the Census Bureau’s tables. Here the people of Hispanic origin, of any race, are one row, and everyone else is counted by race alone (B03002), so the rows add to the whole.

Hispanic origin and race

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People in Mercer County by Hispanic origin and race, ACS 2020–2024
Origin	People	Share	New Jersey	United States
Hispanic or Latino	89,099 ±0	23.1% ±<0.1	22.5% ±<0.1	19.3% ±<0.1
White alone, not Hispanic	164,891 ±602	42.7% ±0.2	50.9% ±<0.1	57.4% ±<0.1
Black alone, not Hispanic	69,099 ±1,027	17.9% ±0.3	12.2% ±<0.1	11.9% ±<0.1
Asian alone, not Hispanic	47,553 ±640	12.3% ±0.2	10.0% ±<0.1	5.9% ±<0.1
American Indian and Alaska Native alone, not Hispanic	213 ±94	0.1% ±<0.1	0.1% ±<0.1	0.5% ±<0.1
Native Hawaiian and Other Pacific Islander alone, not Hispanic	0 to 105	0% to < 0.1%	< 0.1% ±<0.1	0.2% ±<0.1
Some other race alone, not Hispanic	1,900 ±549	0.5% ±0.1	0.8% ±<0.1	0.6% ±<0.1
Two or more races, not Hispanic	13,059 ±1,401	3.4% ±0.4	3.5% ±0.1	4.3% ±<0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Place of birth and citizenship

“Born a citizen outside the states” counts people born in Puerto Rico, the island areas, or abroad to American parents. Naturalized citizens and those who are not citizens together make up the people born abroad (B05002).

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People in Mercer County by place of birth and citizenship, ACS 2020–2024
Born	People	Share	New Jersey	United States
Born in the state	186,376 ±3,788	48.3% ±1.0	50.8% ±0.2	57.3% ±<0.1
Born in another state	82,881 ±2,481	21.5% ±0.6	22.7% ±0.1	26.9% ±<0.1
Born a citizen outside the states	12,300 ±1,467	3.2% ±0.4	2.6% ±<0.1	1.7% ±<0.1
Born abroad	104,307 ±3,420	27.0% ±0.9	23.9% ±0.2	14.1% ±<0.1
Naturalized citizens	48,117 ±2,409	12.5% ±0.6	13.5% ±0.1	7.4% ±<0.1
Not citizens	56,190 ±2,782	14.6% ±0.7	10.5% ±0.1	6.8% ±<0.1

Mercer County among the counties of New Jersey

12th of 21 by population, July 2025. Every one is listed on the New Jersey page.

Counties of New Jersey near Mercer County in population, July 2025
County	July 2025	Change since 2020
Union County	601,863	+4.9%
Camden County	535,799	+2.4%
Passaic County	531,624	+1.6%
Morris County	524,251	+3.2%
Burlington County	481,439	+4.3%
Mercer County	399,289	+3.3%
Somerset County	356,486	+3.5%
Gloucester County	312,638	+3.3%
Atlantic County	278,657	+1.6%
Cumberland County	157,148	+2.2%
Sussex County	148,063	+2.9%

Elsewhere on the site

Sources

Census Bureau population estimates — counties and Puerto Rico municipios, with components of change — U.S. Census Bureau · U.S. Government work · retrieved September 25, 2026
American Community Survey 5-year estimates — table-based Summary File · U.S. Government work

Data retrieved September 25, 2026