Delaware County area

Population and density of Delaware County

The Census Bureau estimates that 580,937 people lived in Delaware County on July 1, 2025. That ranks #123 of 3,222 county equivalents nationally and #5 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 576,962, the population has grown by 3,975 (+0.7%), compared with +0.4% for Pennsylvania as a whole.

With 183.8 square miles of land, that is 3,161 people per square mile (1,220 per km²), placing Delaware County #38 nationally for density and #2 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 0.202 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 Delaware County

Delaware County is divided into 49 municipalities and townships. In Pennsylvania, county subdivisions are local governments, and together they cover all of the county’s land and residents.

The most populous is Upper Darby township, with 85,458 residents (14.7% of the county). The largest by land is Radnor township, at 13.8 mi², or 7.5% of the county’s land. The county seat, Media borough, has 5,920 residents. Among those with at least 1,000 residents in 2020, Edgmont township grew fastest since then (+9.9%).

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

Metropolitan area

Delaware County is a central county of the Philadelphia-Camden-Wilmington, PA-NJ-DE-MD Metropolitan Statistical Area, in the Philadelphia, PA metropolitan division. Its 11 county equivalents have 6,329,118 residents on 4,603.2 square miles of land; Delaware County accounts for 4% of the land and 9.2% of the residents. By combined land it ranks #58 of 393 metropolitan areas, and #9 by population. It belongs to the Philadelphia-Reading-Camden, PA-NJ-DE-MD Combined Statistical Area.

ZIP codes

45 ZIP Code Tabulation Areas have land in Delaware County; 39 of them have most of their land inside the county, and the others mainly cover neighboring areas.

190031900819010190131901419015190171901819022190231902619029190321903319036190411904319050190521906019061190631906419070190731907419076190781907919081190821908319085190861908719094190961911319153193121931719319193421937319382

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 Delaware County

Delaware County shares a land border with 5 county equivalents, including 2 in New Jersey and Delaware. It has more land than 1 of them. The largest neighbor is Chester County (750.6 mi²) and the smallest is Philadelphia County (134.3 mi²). Together with its neighbors, Delaware County forms a block of 2,300 mi² of land, of which it holds 8%.

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

Delaware County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 5.6 times as much. Pennsylvania’s county land could hold about 243 areas the size of Delaware County.

Another way to picture it: the same land area would fill a square about 13.6 miles (21.8 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 Delaware County?

Delaware County has more land than 199 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 Delaware County at #3,040 nationally by total area, 17 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 3.6%, compared with a national county-equivalent median of 1.2% — 2.4 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 Delaware 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.