County outline
Where Knox County is located
Area breakdown
Land accounts for 32.2% of Knox County’s measured area and water for 67.8%. Its combined area converts to 2,932.6 square kilometers or approximately 724,656 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 364.902 | 945.092 | 233,537.3 |
| Water | 767.373 | 1,987.487 | 491,118.7 |
| Total | 1,132.275 | 2,932.579 | 724,656 |
How Knox County compares
By original Census land area, Knox County ranks #15 of 16 in Maine and #2642 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.283 times the Maine county-equivalent median of 1,289.2 square miles. It accounts for 1.2% of the combined county land area in the state.
See the complete Maine ranking · What counts as a county equivalent?
Population and density of Knox County
The Census Bureau estimates that 41,117 people lived in Knox County on July 1, 2025. That ranks #1,191 of 3,222 county equivalents nationally and #10 of 16 in Maine. Since the April 1, 2020 estimates base of 40,608, the population has grown by 509 (+1.3%), compared with +3.8% for Maine as a whole.
With 364.9 square miles of land, that is 113 people per square mile (44 per km²), placing Knox County #916 nationally for density and #6 in Maine. The median county equivalent has 47 people per square mile; the Maine median is 51. Put another way, there are about 5.7 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 40,663 | 41,089 | 41,291 | 41,077 | 40,964 | 41,117 |
| Change | — | +426 | +202 | −214 | −113 | +153 |
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 Knox County
Knox County is divided into 20 cities and towns. In Maine, county subdivisions are local governments, and together they cover all of the county’s land and residents.
The most populous is Rockland city, with 7,142 residents (17.4% of the county). The largest by land is Warren town, at 46.5 mi², or 12.7% of the county’s land. Among those with at least 1,000 residents in 2020, Warren town grew fastest since then (+4.7%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Rockland cityCounty seat | 7,142 | +2.8% | 12.8 | 3.5% |
| Camden town | 5,204 | −0.6% | 18.2 | 5% |
| Warren town | 5,099 | +4.7% | 46.5 | 12.7% |
| Rockport town | 3,628 | −0.2% | 21.6 | 5.9% |
| Thomaston town | 2,751 | +0.7% | 10.9 | 3% |
| St. George town | 2,595 | 0% | 25 | 6.9% |
| Union town | 2,444 | +3.1% | 32.2 | 8.8% |
| Hope town | 1,737 | +1.9% | 22 | 6% |
| Washington town | 1,562 | −2% | 38 | 10.4% |
| South Thomaston town | 1,520 | +0.9% | 11.4 | 3.1% |
| Owls Head town | 1,494 | −0.8% | 8.877 | 2.4% |
| Cushing town | 1,482 | −1.5% | 19.2 | 5.3% |
| Appleton town | 1,469 | +3.9% | 32.7 | 9% |
| Vinalhaven town | 1,254 | −2.7% | 23.5 | 6.4% |
| Friendship town | 1,159 | +1.6% | 14.1 | 3.9% |
Show the other 5 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| North Haven town | 432 | +3.1% | 11.4 |
| Isle au Haut town | 84 | −1.2% | 12.5 |
| Matinicus Isle plantation | 50 | −2% | 2.4 |
| Muscle Ridge Islands UT | 8 | 0% | 0.946 |
| Criehaven UT | 3 | 0% | 0.53 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Knox County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Knox County is not part of any metropolitan or micropolitan statistical area in the Office of Management and Budget’s July 2023 delineation; 1,306 other county equivalents are also outside one. These areas are built around an urban core of at least 10,000 people plus the counties tied to it by commuting, so counties outside them are generally rural.
ZIP codes
19 ZIP Code Tabulation Areas have land in Knox County, and each lies mostly inside the county.
04547045630457404645048410484304847048510485304854048550485604858048590486004861048620486304864
ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Post-office-box and single-address ZIP Codes have no tabulation area.
Counties bordering Knox County
Knox County shares a land border with 2 county equivalents. Each of them has more land than Knox County. The largest neighbor is Waldo County (730.2 mi²) and the smallest is Lincoln County (455.9 mi²). Together with its neighbors, Knox County forms a block of 1,551 mi² of land, of which it holds 23.5%.
| Bordering county equivalent | Land mi² | Size vs. Knox | Compare |
|---|---|---|---|
| Waldo County | 730.2 | 2× larger | Compare |
| Lincoln County | 455.9 | 1.2× larger | Compare |
How big is Knox County compared with U.S. states?
Knox County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.8 times as much. Maine’s county land could hold about 85 areas the size of Knox County.
Another way to picture it: the same land area would fill a square about 19.1 miles (30.7 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 Knox County?
Knox County has more land than 580 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 Knox County at #643 nationally by total area, 1,999 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 67.8%, compared with a national county-equivalent median of 1.2% — 66.6 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 Knox County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2641 | Marion County, Georgia | 365.7 | Compare |
| #2642 | Knox County, Maine | 364.9 | This county |
| #2643 | Warren County, Indiana | 364.7 | 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 44.042045, -69.038514. 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: 945,092,550 m²; AWATER: 1,987,486,434 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 Knox County?
Knox County, Maine has 364.9 square miles (945.1 km²) of land and 767.4 square miles of water, for a total area of 1,132.3 square miles. It ranks #2642 of 3,222 U.S. county equivalents by land area.
Is Knox County the largest county in Maine?
No. Knox County ranks #15 of 16 in Maine by land area. The largest is Aroostook County, with 6,671.2 square miles of land.
What counties border Knox County?
Knox County shares a land border with Lincoln County and Waldo County.
What is the population of Knox County?
The Census Bureau estimates Knox County had 41,117 residents on July 1, 2025, ranking #1,191 of 3,222 county equivalents. That is 113 people per square mile of land.
What is the county seat of Knox County?
The county seat of Knox County is Rockland.
What cities and towns are in Knox County?
Knox County has 20 county subdivisions (cities, towns and townships). The most populous five are Rockland city, Camden town, Warren town, Rockport town, and Thomaston town.
Is Knox County part of a metropolitan area?
No. Knox County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Knox County?
19 ZIP Code Tabulation Areas have land in Knox County, and 19 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Knox County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2.8 times as much land.
How many acres of land are in Knox County?
The land measurement converts to approximately 233,537 acres. Including water, total area is approximately 724,656 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.