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Where am ILOCATED

Mercer County, New Jersey

Mercer County, New Jersey, has 399,289 residents (July 2025 estimate). Its county seat is Trenton. It uses Eastern Time and covers 224 sq mi (581 km²) of land.

NewarkJersey CityPaterson
Mercer County in New Jersey
TrentonPrincetonMercervilleWhite Horse
Mercer County and its neighbors (simplified outlines). Open in OpenStreetMap ↗
Resident population, July 2025
399,289
Land area
224 sq mi (581 km²)
County seat or government
Trenton
Time zone
Eastern TimeUTC-05:00 in January; UTC-04:00 in July
Median household income
$100,645 ± $2,565
Median home value
$377,700 ± $6,110
Median rent, with utilities
$1,623 ± $34
Homes lived in by their owners
62.2% ± 1.1 points
County type
County
Metro or micro area
Trenton-Princeton, NJ metro areaCentral county
Water area
4.37 sq mi (11.3 km²)
State
New Jersey
County code (FIPS)
34021
Coordinates (central point)
40.282503, -74.703724
Open this point in the location finder

These coordinates mark a central point for the area, not a street address. Income, home value, rent and homes lived in by their owners: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates, ± margin at 90% confidence; checked on October 13, 2026.

Time zones in Mercer County

Time zoneLocal time and UTC offsetNext clock change
Eastern TimeAmerica/New_YorkUTC-05:00 in January; UTC-04:00 in July. Enable JavaScript for the live clock.Enable JavaScript for upcoming changes.

Near a time-zone line, check where you are with the time-zone finder. Your phone’s setting can differ.

ZIP Code areas, largest first

  1. 0854050,388 people
  2. 0861835,634 people
  3. 0861033,465 people
  4. 0861131,995 people
  5. 0864831,323 people
  6. 0852029,504 people
  7. 0861924,089 people
  8. 0863822,816 people
  9. 0855021,067 people
  10. 0869018,841 people
  11. 0869116,607 people
  12. 0860915,938 people
All 26
  1. 0853413,272 people
  2. 0862913,013 people
  3. 0851212,928 people
  4. 0862011,621 people
  5. 086289,831 people
  6. 085308,119 people
  7. 085587,648 people
  8. 085016,364 people
  9. 085254,522 people
  10. 085444,392 people
  11. 085603,245 people
  12. 085422,533 people
  13. 086081,250 people
  14. 08561325 people

26 ZIP Code areas overlap Mercer County. People counts are 2020–2024 estimates for each whole ZIP area. Mailing ZIPs can differ; check an address with USPS ZIP Code Lookup.

Official county information

Mercer County government website ↗ is the next stop for county offices, tax, voting, jury and records information. A geographic lookup cannot determine eligibility, tax liability or a court obligation.

Townships in Mercer County, largest first

  1. Hamilton Township92,506 people
  2. Ewing Township35,604 people
  3. Lawrence Township32,313 people
  4. West Windsor Township30,479 people
  5. East Windsor Township30,062 people
  6. Hopewell Township17,595 people
  7. Robbinsville Township15,641 people

People counts are American Community Survey 2020–2024 5-year estimates. All townships in New Jersey, by county

School districts in Mercer County, largest first

  1. Hamilton Township School District (Mercer County)92,506 people
  2. Trenton City School District90,338 people
  3. West Windsor-Plainsboro Regional School District54,646 people
  4. East Windsor Regional School District35,982 people
  5. Ewing Township School District35,604 people
  6. Lawrence Township School District (Mercer County)32,313 people
  7. Princeton Public Schools30,756 people
  8. Hopewell Valley Regional School District22,245 people
  9. Robbinsville Township School District15,641 people

Districts with land in the county; a district can cross county lines. People counts are American Community Survey 2020–2024 5-year estimates. A district boundary doesn’t decide which school a student attends.

Cities, towns and communities, largest first

These areas overlap the mapped boundary; an overlap does not mean that every address belongs to both.

  1. Trenton, New Jersey (city)90,338 people
  2. Princeton, New Jersey30,756 people
  3. Mercerville, New Jersey (CDP)13,535 people
  4. Hamilton Square, New Jersey (CDP)11,622 people
  5. White Horse, New Jersey (CDP)10,507 people
  6. Twin Rivers, New Jersey (CDP)8,382 people
  7. Yardville, New Jersey (CDP)6,301 people
  8. Hightstown, New Jersey (borough)5,920 people
  9. Lawrenceville, New Jersey (CDP)3,924 people
  10. Robbinsville Center, New Jersey (CDP)3,777 people
  11. The College of New Jersey, New Jersey (CDP)3,658 people
  12. Groveville, New Jersey (CDP)3,100 people
All 18
  1. Pennington, New Jersey (borough)2,827 people
  2. Princeton Junction, New Jersey (CDP)2,025 people
  3. Hopewell, New Jersey (borough)1,823 people
  4. Washington Crossing, New Jersey (CDP)536 people
  5. Titusville, New Jersey (CDP)501 people
  6. Windsor, New Jersey (CDP)325 people

Bordering areas, nearest first

Distances are straight lines between map points.

  1. Middlesex County, New Jersey19 mi northeast
  2. Somerset County, New Jersey20 mi north
  3. Bucks County, Pennsylvania22 mi west
  4. Hunterdon County, New Jersey22 mi northwest
  5. Burlington County, New Jersey28 mi south
  6. Monmouth County, New Jersey29 mi east

Before using this answer on a form

Use a precise point for address-level questions. A device accuracy circle can cross a boundary; confirm tax, voting or jury details with the responsible office.

Find the county where you are now, check its ZIP area, or check the time zone where you are.

See this county on Census.gov ↗

Areas that only touch the edge

These areas meet the boundary only along a sliver. Most addresses here are not in them; for an address near the line, check with the county.