County outline
Where Northumberland County is located
Area breakdown
Land accounts for 95.9% of Northumberland County’s measured area and water for 4.1%. Its combined area converts to 1,236 square kilometers or approximately 305,427 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 457.678 | 1,185.381 | 292,913.9 |
| Water | 19.552 | 50.639 | 12,513.3 |
| Total | 477.23 | 1,236.02 | 305,427.2 |
How Northumberland County compares
By original Census land area, Northumberland County ranks #49 of 67 in Pennsylvania and #2241 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.701 times the Pennsylvania county-equivalent median of 653.3 square miles. It accounts for 1% of the combined county land area in the state.
See the complete Pennsylvania ranking · What counts as a county equivalent?
Population and density of Northumberland County
The Census Bureau estimates that 89,920 people lived in Northumberland County on July 1, 2025. That ranks #676 of 3,222 county equivalents nationally and #32 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 91,646, the population has declined by 1,726 (−1.9%), compared with +0.4% for Pennsylvania as a whole.
With 457.7 square miles of land, that is 196 people per square mile (76 per km²), placing Northumberland County #647 nationally for density and #27 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 3.3 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 91,544 | 90,978 | 90,075 | 90,139 | 89,969 | 89,920 |
| Change | — | −566 | −903 | +64 | −170 | −49 |
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 Northumberland County
Northumberland County is divided into 36 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 Coal township, with 9,721 residents (10.8% of the county). The largest by land is Shamokin township, at 30.8 mi², or 6.7% of the county’s land. The county seat, Sunbury city, has 9,495 residents. Among those with at least 1,000 residents in 2020, Shamokin township grew fastest since then (+2.1%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Coal township | 9,721 | −4.1% | 26.3 | 5.7% |
| Sunbury cityCounty seat | 9,495 | −2.2% | 2.007 | 0.4% |
| Shamokin city | 6,764 | −2.7% | 0.825 | 0.2% |
| Milton borough | 6,457 | −2.4% | 3.469 | 0.8% |
| Mount Carmel borough | 5,579 | −2.4% | 0.662 | 0.1% |
| Delaware township | 4,287 | −0.6% | 30.1 | 6.6% |
| Ralpho township | 4,181 | −0.2% | 18.5 | 4% |
| Point township | 3,818 | −0.9% | 25.1 | 5.5% |
| Northumberland borough | 3,800 | −2.3% | 1.61 | 0.4% |
| Kulpmont borough | 2,688 | −2.6% | 0.959 | 0.2% |
| West Chillisquaque township | 2,614 | +0.6% | 12.9 | 2.8% |
| Mount Carmel township | 2,469 | −1.6% | 21.6 | 4.7% |
| Upper Augusta township | 2,432 | −1.7% | 20 | 4.4% |
| Shamokin township | 2,430 | +2.1% | 30.8 | 6.7% |
| Rockefeller township | 2,302 | −2.1% | 20.6 | 4.5% |
Show the other 21 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Watsontown borough | 2,188 | −1.9% | 0.709 |
| Riverside borough | 1,991 | −2.1% | 4.94 |
| Lewis township | 1,928 | −0.6% | 26.4 |
| Turbot township | 1,794 | −0.7% | 13.8 |
| Zerbe township | 1,769 | −2.1% | 11.1 |
| Lower Mahanoy township | 1,603 | −1.6% | 22 |
| Rush township | 1,166 | −2.4% | 26.6 |
| Lower Augusta township | 1,030 | −1.2% | 18.3 |
| Jackson township | 888 | −1.7% | 12.5 |
| Jordan township | 766 | −2.3% | 17.2 |
| Washington township | 766 | +2.4% | 18.1 |
| Turbotville borough | 660 | −2.9% | 0.451 |
| East Chillisquaque township | 659 | −1.9% | 8.026 |
| Upper Mahanoy township | 638 | −1.5% | 23.3 |
| East Cameron township | 621 | −0.6% | 11.7 |
| Marion Heights borough | 552 | −2% | 0.153 |
| West Cameron township | 492 | −0.4% | 11.9 |
| Little Mahanoy township | 431 | +0.7% | 10.9 |
| Herndon borough | 341 | −2.8% | 0.791 |
| Snydertown borough | 316 | −2.2% | 3.433 |
| McEwensville borough | 284 | −0.7% | 0.117 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Northumberland County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Northumberland County is a central county of the Sunbury, PA Micropolitan Statistical Area. Its 2 county equivalents have 107,788 residents on 588 square miles of land; Northumberland County accounts for 77.8% of the land and 83.4% of the residents. By combined land it ranks #364 of 542 micropolitan areas, and #25 by population. It belongs to the Bloomsburg-Berwick-Sunbury, PA Combined Statistical Area.
| County equivalent | Population 2025 | Land mi² |
|---|---|---|
| Northumberland County | 89,920 | 457.7 |
| Montour County | 17,868 | 130.3 |
ZIP codes
28 ZIP Code Tabulation Areas have land in Northumberland County; 22 of them have most of their land inside the county, and the others mainly cover neighboring areas.
17017177301774917756177721777717801178211782317824178301783217834178361784017847178501785117857178601786517866178671786817872178811794117964
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 Northumberland County
Northumberland County shares a land border with 8 county equivalents. It has more land than 4 of them. The largest neighbor is Lycoming County (1,228.9 mi²) and the smallest is Montour County (130.3 mi²). Together with its neighbors, Northumberland County forms a block of 4,640 mi² of land, of which it holds 9.9%.
| Bordering county equivalent | Land mi² | Size vs. Northumberland | Compare |
|---|---|---|---|
| Lycoming County | 1,228.9 | 2.7× larger | Compare |
| Schuylkill County | 778.8 | 1.7× larger | Compare |
| Dauphin County | 524.9 | 1.1× larger | Compare |
| Columbia County | 483.3 | 1.1× larger | Compare |
| Juniata County | 391.4 | 1.2× smaller | Compare |
| Snyder County | 328.8 | 1.4× smaller | Compare |
| Union County | 316 | 1.4× smaller | Compare |
| Montour County | 130.3 | 3.5× smaller | Compare |
How big is Northumberland County compared with U.S. states?
Northumberland County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.3 times as much. Pennsylvania’s county land could hold about 98 areas the size of Northumberland County.
Another way to picture it: the same land area would fill a square about 21.4 miles (34.4 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 Northumberland County?
Northumberland County has more land than 981 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 Northumberland County at #2,253 nationally by total area, 12 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 4.1%, compared with a national county-equivalent median of 1.2% — 2.9 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 Northumberland County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2240 | St. Joseph County, Indiana | 457.8 | Compare |
| #2241 | Northumberland County, Pennsylvania | 457.7 | This county |
| #2242 | Oktibbeha County, Mississippi | 457.6 | 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 40.852571, -76.705964. 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: 1,185,380,624 m²; AWATER: 50,638,534 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 Northumberland County?
Northumberland County, Pennsylvania has 457.7 square miles (1,185.4 km²) of land and 19.6 square miles of water, for a total area of 477.2 square miles. It ranks #2241 of 3,222 U.S. county equivalents by land area.
Is Northumberland County the largest county in Pennsylvania?
No. Northumberland County ranks #49 of 67 in Pennsylvania by land area. The largest is Lycoming County, with 1,228.9 square miles of land.
What counties border Northumberland County?
Northumberland County shares a land border with Montour County, Union County, Snyder County, Schuylkill County, Dauphin County, Columbia County, Lycoming County, and Juniata County.
What is the population of Northumberland County?
The Census Bureau estimates Northumberland County had 89,920 residents on July 1, 2025, ranking #676 of 3,222 county equivalents. That is 196 people per square mile of land.
What is the county seat of Northumberland County?
The county seat of Northumberland County is Sunbury.
What cities and towns are in Northumberland County?
Northumberland County has 36 county subdivisions (cities, towns and townships). The most populous five are Coal township, Sunbury city, Shamokin city, Milton borough, and Mount Carmel borough.
Is Northumberland County part of a metropolitan area?
Yes. It is a central county of the Sunbury, PA Micropolitan Statistical Area, which has 2 county equivalents and 107,788 residents.
How many ZIP codes are in Northumberland County?
28 ZIP Code Tabulation Areas have land in Northumberland County, and 22 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Northumberland County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2.3 times as much land.
How many acres of land are in Northumberland County?
The land measurement converts to approximately 292,914 acres. Including water, total area is approximately 305,427 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.