Union County area

Population and density of Union County

The Census Bureau estimates that 601,863 people lived in Union County on July 1, 2025. That ranks #118 of 3,222 county equivalents nationally and #7 of 21 in New Jersey. Since the April 1, 2020 estimates base of 575,332, the population has grown by 26,531 (+4.6%), compared with +2.8% for New Jersey as a whole.

With 102.8 square miles of land, that is 5,857 people per square mile (2,261 per km²), placing Union County #17 nationally for density and #3 in New Jersey. The median county equivalent has 47 people per square mile; the New Jersey median is 1,137. Put another way, there are about 0.109 acres of land per resident.

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Union County

Union County is divided into 21 municipalities and townships. In New Jersey, county subdivisions are local governments, and together they cover all of the county’s land and residents.

The most populous is Elizabeth city, with 141,675 residents (23.5% of the county), and it is also the largest by land at 12.3 mi². Among those with at least 1,000 residents in 2020, Garwood borough grew fastest since then (+21.2%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Union County. Land: 2026 Census Gazetteer. How communities are listed.

Metropolitan area

Union County is a central county of the New York-Newark-Jersey City, NY-NJ Metropolitan Statistical Area, in the Newark, NJ metropolitan division. Its 22 county equivalents have 20,112,448 residents on 6,139.7 square miles of land; Union County accounts for 1.7% of the land and 3% of the residents. By combined land it ranks #34 of 393 metropolitan areas, and #1 by population. It belongs to the New York-Newark, NY-NJ-CT-PA Combined Statistical Area.

ZIP codes

27 ZIP Code Tabulation Areas have land in Union County; 26 of them have most of their land inside the county, and the others mainly cover neighboring areas.

070160702307027070330703607060070620706307065070660707607081070830708807090070920720107202072030720407205072060720807901079220797408812

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Union County

Union County shares a land border with 4 county equivalents. Each of them has more land than Union County. The largest neighbor is Morris County (461 mi²) and the smallest is Essex County (126.1 mi²). Together with its neighbors, Union County forms a block of 1,301.1 mi² of land, of which it holds 7.9%.

How big is Union County compared with U.S. states?

Union County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 10 times as much. New Jersey’s county land could hold about 72 areas the size of Union County.

Another way to picture it: the same land area would fill a square about 10.1 miles (16.3 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Union County?

Union County has more land than 133 of the other 3,221 county equivalents in the dataset.

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Union County at #3,105 nationally by total area, 16 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 2.5%, compared with a national county-equivalent median of 1.2% — 1.3 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Union County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.