County outline
Where Adams County is located
Area breakdown
Land accounts for 99.4% of Adams County’s measured area and water for 0.6%. Its combined area converts to 1,351.3 square kilometers or approximately 333,902 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 518.576 | 1,343.106 | 331,888.6 |
| Water | 3.146 | 8.148 | 2,013.4 |
| Total | 521.722 | 1,351.254 | 333,902.1 |
How Adams County compares
By original Census land area, Adams County ranks #45 of 67 in Pennsylvania and #2013 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.794 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 Adams County
The Census Bureau estimates that 107,594 people lived in Adams County on July 1, 2025. That ranks #592 of 3,222 county equivalents nationally and #31 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 103,854, the population has grown by 3,740 (+3.6%), compared with +0.4% for Pennsylvania as a whole.
With 518.6 square miles of land, that is 207 people per square mile (80 per km²), placing Adams County #630 nationally for density and #26 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 3.1 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 103,814 | 105,728 | 105,994 | 106,945 | 107,155 | 107,594 |
| Change | — | +1,914 | +266 | +951 | +210 | +439 |
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 Adams County
Adams County is divided into 34 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 Gettysburg borough, with 8,365 residents (7.8% of the county). The largest by land is Franklin township, at 68.2 mi², or 13.1% of the county’s land. Among those with at least 1,000 residents in 2020, Gettysburg borough grew fastest since then (+17.7%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Gettysburg boroughCounty seat | 8,365 | +17.7% | 1.661 | 0.3% |
| Conewago township | 8,075 | +2.6% | 10.4 | 2% |
| Cumberland township | 7,219 | +2.6% | 33.4 | 6.4% |
| Oxford township | 6,089 | +2.5% | 9.529 | 1.8% |
| Reading township | 5,958 | +2.7% | 26.3 | 5.1% |
| Straban township | 4,968 | +2.3% | 34.4 | 6.6% |
| Littlestown borough | 4,895 | +2.4% | 1.83 | 0.4% |
| Mount Pleasant township | 4,797 | +2.7% | 30.4 | 5.9% |
| Franklin township | 4,781 | +2.3% | 68.2 | 13.1% |
| Carroll Valley borough | 4,051 | +2.7% | 5.377 | 1% |
| Mount Joy township | 3,881 | +2.6% | 26 | 5% |
| Menallen township | 3,802 | +2.7% | 42.7 | 8.2% |
| Union township | 3,164 | +2.6% | 17.3 | 3.3% |
| McSherrystown borough | 3,150 | +2.4% | 0.512 | 0.1% |
| Germany township | 2,913 | +2.6% | 10.8 | 2.1% |
Show the other 19 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Hamilton township | 2,778 | +2.5% | 13.5 |
| Latimore township | 2,715 | +2.6% | 21.1 |
| Butler township | 2,626 | +2.7% | 23.9 |
| Berwick township | 2,475 | +3% | 7.696 |
| Huntington township | 2,438 | +2.6% | 25.1 |
| Tyrone township | 2,355 | +2.8% | 21.5 |
| Hamiltonban township | 2,347 | +2.5% | 39.1 |
| New Oxford borough | 1,912 | +2.5% | 0.619 |
| Bonneauville borough | 1,802 | +2.5% | 0.966 |
| East Berlin borough | 1,582 | +2.4% | 0.703 |
| Liberty township | 1,413 | +2.6% | 16.3 |
| Biglerville borough | 1,240 | +2.3% | 0.651 |
| Abbottstown borough | 1,048 | +2.4% | 0.546 |
| Highland township | 1,020 | +2.5% | 12.1 |
| Arendtsville borough | 890 | +2.5% | 0.806 |
| Freedom township | 847 | +2.4% | 14 |
| Bendersville borough | 757 | +2.4% | 0.452 |
| York Springs borough | 699 | +2.8% | 0.198 |
| Fairfield borough | 542 | +2.3% | 0.673 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Adams County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Adams County is a central county of the Gettysburg, PA Metropolitan Statistical Area. Adams County is the area’s only county equivalent, so the metro area has the same 518.6 square miles of land. By combined land it ranks #355 of 393 metropolitan areas, and #355 by population. It belongs to the Harrisburg-York-Lebanon, PA Combined Statistical Area.
ZIP codes
18 ZIP Code Tabulation Areas have land in Adams County; 14 of them have most of their land inside the county, and the others mainly cover neighboring areas.
170191722217301173031730417306173071731617320173241732517331173401734317344173501735317372
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 Adams County
Adams County shares a land border with 5 county equivalents, including 2 in Maryland. It has more land than 1 of them. The largest neighbor is York County (904.4 mi²) and the smallest is Carroll County (447.6 mi²). Together with its neighbors, Adams County forms a block of 3,849 mi² of land, of which it holds 13.5%.
| Bordering county equivalent | Land mi² | Size vs. Adams | Compare |
|---|---|---|---|
| York County | 904.4 | 1.7× larger | Compare |
| Franklin County | 772.3 | 1.5× larger | Compare |
| Frederick CountyMaryland | 660.7 | 1.3× larger | Compare |
| Cumberland County | 545.5 | 1.1× larger | Compare |
| Carroll CountyMaryland | 447.6 | 1.2× smaller | Compare |
How big is Adams County compared with U.S. states?
Adams 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 86 areas the size of Adams County.
Another way to picture it: the same land area would fill a square about 22.8 miles (36.6 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 Adams County?
Adams County has more land than 1,209 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 Adams County at #2,098 nationally by total area, 85 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 0.6%, compared with a national county-equivalent median of 1.2% — 0.6 percentage points lower. 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 Adams County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2012 | Tioga County, New York | 518.8 | Compare |
| #2013 | Adams County, Pennsylvania | 518.6 | This county |
| #2014 | Sussex County, New Jersey | 518.5 | 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 39.869437, -77.217750. 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: 1,343,104,823 m²; AWATER: 8,147,591 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 Adams County?
Adams County, Pennsylvania has 518.6 square miles (1,343.1 km²) of land and 3.146 square miles of water, for a total area of 521.7 square miles. It ranks #2013 of 3,222 U.S. county equivalents by land area.
Is Adams County the largest county in Pennsylvania?
No. Adams County ranks #45 of 67 in Pennsylvania by land area. The largest is Lycoming County, with 1,228.9 square miles of land.
What counties border Adams County?
Adams County shares a land border with York County, Cumberland County, Franklin County, Frederick County, Maryland, and Carroll County, Maryland.
What is the population of Adams County?
The Census Bureau estimates Adams County had 107,594 residents on July 1, 2025, ranking #592 of 3,222 county equivalents. That is 207 people per square mile of land.
What is the county seat of Adams County?
The county seat of Adams County is Gettysburg.
What cities and towns are in Adams County?
Adams County has 34 county subdivisions (cities, towns and townships). The most populous five are Gettysburg borough, Conewago township, Cumberland township, Oxford township, and Reading township.
Is Adams County part of a metropolitan area?
Yes. It is a central county of the Gettysburg, PA Metropolitan Statistical Area.
How many ZIP codes are in Adams County?
18 ZIP Code Tabulation Areas have land in Adams County, and 14 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Adams 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 Adams County?
The land measurement converts to approximately 331,889 acres. Including water, total area is approximately 333,902 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.