County outline
Where Rockingham County is located
Area breakdown
Land accounts for 87.5% of Rockingham County’s measured area and water for 12.5%. Its combined area converts to 2,059.7 square kilometers or approximately 508,959 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 695.554 | 1,801.477 | 445,154.6 |
| Water | 99.694 | 258.206 | 63,804.2 |
| Total | 795.248 | 2,059.683 | 508,958.7 |
How Rockingham County compares
By original Census land area, Rockingham County ranks #7 of 10 in New Hampshire and #1339 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.879 times the New Hampshire county-equivalent median of 791.6 square miles. It accounts for 7.8% of the combined county land area in the state.
See the complete New Hampshire ranking · What counts as a county equivalent?
Population and density of Rockingham County
The Census Bureau estimates that 324,077 people lived in Rockingham County on July 1, 2025. That ranks #232 of 3,222 county equivalents nationally and #2 of 10 in New Hampshire. Since the April 1, 2020 estimates base of 314,193, the population has grown by 9,884 (+3.1%), compared with +2.7% for New Hampshire as a whole.
With 695.6 square miles of land, that is 466 people per square mile (180 per km²), placing Rockingham County #361 nationally for density and #2 in New Hampshire. The median county equivalent has 47 people per square mile; the New Hampshire median is 136. Put another way, there are about 1.4 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 314,633 | 318,370 | 319,262 | 320,441 | 322,001 | 324,077 |
| Change | — | +3,737 | +892 | +1,179 | +1,560 | +2,076 |
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 Rockingham County
Rockingham County is divided into 37 cities and towns. In New Hampshire, county subdivisions are local governments, and together they cover all of the county’s land and residents.
The most populous is Derry town, with 33,990 residents (10.5% of the county). The largest by land is Deerfield town, at 50.8 mi², or 7.3% of the county’s land. The county seat, Brentwood town, has 4,923 residents. Among those with at least 1,000 residents in 2020, Epping town grew fastest since then (+11.8%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Derry town | 33,990 | −0.3% | 35.5 | 5.1% |
| Salem town | 31,868 | +5.9% | 24.9 | 3.6% |
| Londonderry town | 27,844 | +6.9% | 42 | 6% |
| Portsmouth city | 23,028 | +4.9% | 15.7 | 2.3% |
| Hampton town | 16,381 | +1% | 12.9 | 1.9% |
| Windham town | 16,259 | +2.8% | 26.7 | 3.8% |
| Exeter town | 16,213 | +0.9% | 19.6 | 2.8% |
| Raymond town | 11,050 | +3.4% | 28.8 | 4.1% |
| Newmarket town | 9,647 | +2.4% | 12.6 | 1.8% |
| Hampstead town | 9,110 | +1.3% | 13.4 | 1.9% |
| Seabrook town | 8,430 | +0.3% | 8.977 | 1.3% |
| Epping town | 7,973 | +11.8% | 26 | 3.7% |
| Plaistow town | 7,848 | +0.3% | 10.6 | 1.5% |
| Stratham town | 7,735 | +0.9% | 15.1 | 2.2% |
| Atkinson town | 7,397 | +4.3% | 11.2 | 1.6% |
Show the other 22 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Sandown town | 6,753 | +2.9% | 13.9 |
| Auburn town | 6,336 | +6.3% | 25.4 |
| Kingston town | 6,288 | +1.5% | 19.8 |
| Rye town | 5,689 | +2.8% | 12.6 |
| Nottingham town | 5,490 | +5% | 46.5 |
| Chester town | 5,322 | +1.9% | 26 |
| Deerfield town | 4,989 | +2.9% | 50.8 |
| Brentwood townCounty seat | 4,923 | +9.8% | 16.8 |
| Fremont town | 4,923 | +3.9% | 17.2 |
| Newton town | 4,851 | +0.6% | 9.813 |
| Northwood town | 4,757 | +2.5% | 28.1 |
| Danville town | 4,650 | +5.5% | 11.6 |
| North Hampton town | 4,526 | −0.3% | 13.9 |
| Candia town | 4,248 | +5.8% | 30.3 |
| Greenland town | 4,143 | +1.9% | 10.5 |
| East Kingston town | 2,434 | −0.2% | 9.917 |
| Hampton Falls town | 2,379 | −0.9% | 12.2 |
| Kensington town | 2,092 | −0% | 12 |
| Newfields town | 1,775 | +0.1% | 7.091 |
| New Castle town | 997 | +0.2% | 0.809 |
| South Hampton town | 892 | +0.1% | 8.024 |
| Newington town | 847 | +4.3% | 8.224 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Rockingham County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Rockingham County is a central county of the Boston-Cambridge-Newton, MA-NH Metropolitan Statistical Area, in the Rockingham County-Strafford County, NH metropolitan division. Its 7 county equivalents have 5,034,221 residents on 3,486.3 square miles of land; Rockingham County accounts for 20% of the land and 6.4% of the residents. By combined land it ranks #84 of 393 metropolitan areas, and #11 by population. It belongs to the Boston-Worcester-Providence, MA-RI-NH Combined Statistical Area.
| County equivalent | Population 2025 | Land mi² |
|---|---|---|
| Middlesex CountyMassachusetts | 1,669,979 | 817.9 |
| Essex CountyMassachusetts | 826,653 | 492.5 |
| Suffolk CountyMassachusetts | 791,891 | 58.3 |
| Norfolk CountyMassachusetts | 739,749 | 396.1 |
| Plymouth CountyMassachusetts | 546,829 | 658.5 |
| Rockingham County | 324,077 | 695.6 |
| Strafford County | 135,043 | 367.5 |
ZIP codes
38 ZIP Code Tabulation Areas have land in Rockingham County; 36 of them have most of their land inside the county, and the others mainly cover neighboring areas.
0303203034030360303703038030420304403053030770307903087031030310403261032900329103801038110381903826038270383303840038410384203844038480385403856038570385803862038650387003871038730387403885
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 Rockingham County
Rockingham County shares a land border with 5 county equivalents, including 2 in Massachusetts and Maine. It has more land than 2 of them. The largest neighbor is York County (991.2 mi²) and the smallest is Strafford County (367.5 mi²). Together with its neighbors, Rockingham County forms a block of 4,356.1 mi² of land, of which it holds 16%.
| Bordering county equivalent | Land mi² | Size vs. Rockingham | Compare |
|---|---|---|---|
| York CountyMaine | 991.2 | 1.4× larger | Compare |
| Merrimack County | 932.9 | 1.3× larger | Compare |
| Hillsborough County | 876.5 | 1.3× larger | Compare |
| Essex CountyMassachusetts | 492.5 | 1.4× smaller | Compare |
| Strafford County | 367.5 | 1.9× smaller | Compare |
How big is Rockingham County compared with U.S. states?
Rockingham County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.5 times as much. New Hampshire’s county land could hold about 13 areas the size of Rockingham County.
Another way to picture it: the same land area would fill a square about 26.4 miles (42.4 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 Rockingham County?
Rockingham County has more land than 1,883 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 Rockingham County at #1,195 nationally by total area, 144 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 12.5%, compared with a national county-equivalent median of 1.2% — 11.4 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 Rockingham County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1338 | Concordia Parish, Louisiana | 695.7 | Compare |
| #1339 | Rockingham County, New Hampshire | 695.6 | This county |
| #1340 | Noxubee County, Mississippi | 695.4 | 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 42.988661, -71.099082. 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: 1,801,476,227 m²; AWATER: 258,205,459 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 Rockingham County?
Rockingham County, New Hampshire has 695.6 square miles (1,801.5 km²) of land and 99.7 square miles of water, for a total area of 795.2 square miles. It ranks #1339 of 3,222 U.S. county equivalents by land area.
Is Rockingham County the largest county in New Hampshire?
No. Rockingham County ranks #7 of 10 in New Hampshire by land area. The largest is Coos County, with 1,794.6 square miles of land.
What counties border Rockingham County?
Rockingham County shares a land border with Strafford County, Essex County, Massachusetts, Hillsborough County, Merrimack County, and York County, Maine.
What is the population of Rockingham County?
The Census Bureau estimates Rockingham County had 324,077 residents on July 1, 2025, ranking #232 of 3,222 county equivalents. That is 466 people per square mile of land.
What is the county seat of Rockingham County?
The county seat of Rockingham County is Brentwood.
What cities and towns are in Rockingham County?
Rockingham County has 37 county subdivisions (cities, towns and townships). The most populous five are Derry town, Salem town, Londonderry town, Portsmouth city, and Hampton town.
Is Rockingham County part of a metropolitan area?
Yes. It is a central county of the Boston-Cambridge-Newton, MA-NH Metropolitan Statistical Area, which has 7 county equivalents and 5,034,221 residents.
How many ZIP codes are in Rockingham County?
38 ZIP Code Tabulation Areas have land in Rockingham County, and 36 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Rockingham County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.5 times as much land.
How many acres of land are in Rockingham County?
The land measurement converts to approximately 445,155 acres. Including water, total area is approximately 508,959 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.