County outline
Where Dauphin County is located
Area breakdown
Land accounts for 94% of Dauphin County’s measured area and water for 6%. Its combined area converts to 1,445.5 square kilometers or approximately 357,180 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 524.87 | 1,359.407 | 335,916.8 |
| Water | 33.223 | 86.047 | 21,262.7 |
| Total | 558.093 | 1,445.454 | 357,179.5 |
How Dauphin County compares
By original Census land area, Dauphin County ranks #44 of 67 in Pennsylvania and #1994 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.803 times the Pennsylvania county-equivalent median of 653.3 square miles. It accounts for 1.2% of the combined county land area in the state.
See the complete Pennsylvania ranking · What counts as a county equivalent?
Population and density of Dauphin County
The Census Bureau estimates that 293,351 people lived in Dauphin County on July 1, 2025. That ranks #252 of 3,222 county equivalents nationally and #14 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 286,408, the population has grown by 6,943 (+2.4%), compared with +0.4% for Pennsylvania as a whole.
With 524.9 square miles of land, that is 559 people per square mile (216 per km²), placing Dauphin County #312 nationally for density and #10 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 1.1 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 286,694 | 288,284 | 288,943 | 290,947 | 292,917 | 293,351 |
| Change | — | +1,590 | +659 | +2,004 | +1,970 | +434 |
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 Dauphin County
Dauphin County is divided into 40 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 Lower Paxton township, with 55,564 residents (18.9% of the county). The largest by land is Middle Paxton township, at 54.4 mi², or 10.4% of the county’s land. The county seat, Harrisburg city, has 50,522 residents. Among those with at least 1,000 residents in 2020, West Hanover township grew fastest since then (+8.5%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Lower Paxton township | 55,564 | +3.7% | 28.2 | 5.4% |
| Harrisburg cityCounty seat | 50,522 | +0.9% | 8.119 | 1.5% |
| Susquehanna township | 28,434 | +6.2% | 13.4 | 2.5% |
| Swatara township | 27,936 | +0.5% | 13 | 2.5% |
| Derry township | 25,179 | +1.7% | 27.1 | 5.2% |
| West Hanover township | 11,601 | +8.5% | 23.2 | 4.4% |
| Lower Swatara township | 10,043 | +5.4% | 12.3 | 2.3% |
| Middletown borough | 9,776 | +2.5% | 2.03 | 0.4% |
| South Hanover township | 7,372 | +2.3% | 11.2 | 2.1% |
| Steelton borough | 6,328 | +1.1% | 1.895 | 0.4% |
| East Hanover township | 6,100 | +1.4% | 40.2 | 7.7% |
| Middle Paxton township | 5,114 | +1.5% | 54.4 | 10.4% |
| Londonderry township | 4,925 | +0.6% | 22.8 | 4.3% |
| Hummelstown borough | 4,492 | −0.2% | 1.242 | 0.2% |
| Upper Paxton township | 4,041 | +0.8% | 25.9 | 4.9% |
Show the other 25 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Halifax township | 3,352 | +0.1% | 27.6 |
| Penbrook borough | 3,243 | −0.6% | 0.447 |
| Conewago township | 3,067 | +3.9% | 16.7 |
| Highspire borough | 2,725 | −0.4% | 0.719 |
| Millersburg borough | 2,540 | −0.2% | 0.759 |
| Washington township | 2,133 | 0% | 17.7 |
| Lykens borough | 1,856 | −0.2% | 1.22 |
| Jackson township | 1,852 | +1.5% | 40.1 |
| Paxtang borough | 1,632 | −0.7% | 0.406 |
| Lykens township | 1,628 | +3.6% | 26.5 |
| Elizabethville borough | 1,347 | −0.1% | 0.547 |
| Wayne township | 1,299 | +2.4% | 13.9 |
| Williamstown borough | 1,298 | −0.5% | 0.259 |
| Wiconisco township | 1,157 | −0.1% | 9.761 |
| Royalton borough | 1,133 | −0.4% | 0.318 |
| Williams township | 1,062 | −0.1% | 8.832 |
| Mifflin township | 814 | −0.5% | 15.5 |
| Halifax borough | 810 | +1.6% | 0.336 |
| Dauphin borough | 790 | −0.4% | 0.428 |
| Gratz borough | 750 | +0.1% | 2.949 |
| Jefferson township | 365 | +0.8% | 24.4 |
| Berrysburg borough | 323 | −0.6% | 0.606 |
| Pillow borough | 288 | −1% | 0.493 |
| Reed township | 235 | 0% | 5.935 |
| Rush township | 225 | 0% | 23.5 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Dauphin County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Dauphin County is a central county of the Harrisburg-Carlisle, PA Metropolitan Statistical Area. Its 3 county equivalents have 617,427 residents on 1,621.8 square miles of land; Dauphin County accounts for 32.4% of the land and 47.5% of the residents. By combined land it ranks #200 of 393 metropolitan areas, and #96 by population. It belongs to the Harrisburg-York-Lebanon, PA Combined Statistical Area.
| County equivalent | Population 2025 | Land mi² |
|---|---|---|
| Dauphin County | 293,351 | 524.9 |
| Cumberland County | 277,270 | 545.5 |
| Perry County | 46,806 | 551.5 |
ZIP codes
31 ZIP Code Tabulation Areas have land in Dauphin County; 26 of them have most of their land inside the county, and the others mainly cover neighboring areas.
17005170171701817020170221702317028170301703217033170341703617048170571706117078170801709717098171011710217103171041710917110171111711217113171201797817980
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 Dauphin County
Dauphin County shares a land border with 7 county equivalents. It has more land than 2 of them. The largest neighbor is Lancaster County (943.9 mi²) and the smallest is Lebanon County (361.8 mi²). Together with its neighbors, Dauphin County forms a block of 5,068.4 mi² of land, of which it holds 10.4%.
| Bordering county equivalent | Land mi² | Size vs. Dauphin | Compare |
|---|---|---|---|
| Lancaster County | 943.9 | 1.8× larger | Compare |
| York County | 904.4 | 1.7× larger | Compare |
| Schuylkill County | 778.8 | 1.5× larger | Compare |
| Perry County | 551.5 | 1.1× larger | Compare |
| Cumberland County | 545.5 | about the same | Compare |
| Northumberland County | 457.7 | 1.1× smaller | Compare |
| Lebanon County | 361.8 | 1.5× smaller | Compare |
How big is Dauphin County compared with U.S. states?
Dauphin 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 times as much. Pennsylvania’s county land could hold about 85 areas the size of Dauphin County.
Another way to picture it: the same land area would fill a square about 22.9 miles (36.9 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 Dauphin County?
Dauphin County has more land than 1,228 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 Dauphin County at #1,977 nationally by total area, 17 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.
Its water share is 6%, compared with a national county-equivalent median of 1.2% — 4.8 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 Dauphin County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1993 | Blair County, Pennsylvania | 525.1 | Compare |
| #1994 | Dauphin County, Pennsylvania | 524.9 | This county |
| #1995 | Mecklenburg County, North Carolina | 523.6 | Compare |
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.
Representative coordinates
The Census internal point is 40.411006, -76.799101. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.
Source and precision
U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 1,359,407,377 m²; AWATER: 86,047,350 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How big is Dauphin County?
Dauphin County, Pennsylvania has 524.9 square miles (1,359.4 km²) of land and 33.2 square miles of water, for a total area of 558.1 square miles. It ranks #1994 of 3,222 U.S. county equivalents by land area.
Is Dauphin County the largest county in Pennsylvania?
No. Dauphin County ranks #44 of 67 in Pennsylvania by land area. The largest is Lycoming County, with 1,228.9 square miles of land.
What counties border Dauphin County?
Dauphin County shares a land border with Lebanon County, Perry County, Northumberland County, Schuylkill County, York County, Lancaster County, and Cumberland County.
What is the population of Dauphin County?
The Census Bureau estimates Dauphin County had 293,351 residents on July 1, 2025, ranking #252 of 3,222 county equivalents. That is 559 people per square mile of land.
What is the county seat of Dauphin County?
The county seat of Dauphin County is Harrisburg.
What cities and towns are in Dauphin County?
Dauphin County has 40 county subdivisions (cities, towns and townships). The most populous five are Lower Paxton township, Harrisburg city, Susquehanna township, Swatara township, and Derry township.
Is Dauphin County part of a metropolitan area?
Yes. It is a central county of the Harrisburg-Carlisle, PA Metropolitan Statistical Area, which has 3 county equivalents and 617,427 residents.
How many ZIP codes are in Dauphin County?
31 ZIP Code Tabulation Areas have land in Dauphin County, and 26 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Dauphin County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2 times as much land.
How many acres of land are in Dauphin County?
The land measurement converts to approximately 335,917 acres. Including water, total area is approximately 357,180 acres. One square mile equals 640 acres.
Why might another source show a different area?
Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.
Can this establish a property boundary?
No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.