Warren County area

Population and density of Warren County

The Census Bureau estimates that 112,953 people lived in Warren County on July 1, 2025. That ranks #574 of 3,222 county equivalents nationally and #19 of 21 in New Jersey. Since the April 1, 2020 estimates base of 109,630, the population has grown by 3,323 (+3%), compared with +2.8% for New Jersey as a whole.

With 356.5 square miles of land, that is 317 people per square mile (122 per km²), placing Warren County #489 nationally for density and #18 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 2 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 Warren County

Warren County is divided into 22 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 Phillipsburg town, with 15,456 residents (13.7% of the county). The largest by land is Hardwick township, at 37.5 mi², or 10.5% of the county’s land. The county seat, Belvidere town, has 2,551 residents. Among those with at least 1,000 residents in 2020, Pohatcong township grew fastest since then (+10.4%).

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

Metropolitan area

Warren County is a central county of the Allentown-Bethlehem-Easton, PA-NJ Metropolitan Statistical Area. Its 4 county equivalents have 887,615 residents on 1,453 square miles of land; Warren County accounts for 24.5% of the land and 12.7% of the residents. By combined land it ranks #227 of 393 metropolitan areas, and #70 by population. It belongs to the Allentown-Bethlehem-East Stroudsburg, PA-NJ Combined Statistical Area.

ZIP codes

22 ZIP Code Tabulation Areas have land in Warren County; 16 of them have most of their land inside the county, and the others mainly cover neighboring areas.

07820078210782307825078310783207833078380784007844078460786007863078650787407880078820880208804088270886508886

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 Warren County

Warren County shares a land border with 6 county equivalents, including 3 in Pennsylvania. Each of them has more land than Warren County. The largest neighbor is Monroe County (608.4 mi²) and the smallest is Northampton County (369.8 mi²). Together with its neighbors, Warren County forms a block of 3,346.5 mi² of land, of which it holds 10.7%.

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

Warren County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.9 times as much. New Jersey’s county land could hold about 21 areas the size of Warren County.

Another way to picture it: the same land area would fill a square about 18.9 miles (30.4 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 Warren County?

Warren County has more land than 554 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 Warren County at #2,703 nationally by total area, 35 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 1.7%, compared with a national county-equivalent median of 1.2% — 0.5 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 Warren 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.