County outline
Where Green County is located
Area breakdown
Land accounts for 99.9% of Green County’s measured area and water for 0.1%. Its combined area converts to 1,514 square kilometers or approximately 374,113 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 584.044 | 1,512.667 | 373,788.2 |
| Water | 0.507 | 1.313 | 324.5 |
| Total | 584.551 | 1,513.98 | 374,112.6 |
How Green County compares
By original Census land area, Green County ranks #50 of 72 in Wisconsin and #1684 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.776 times the Wisconsin county-equivalent median of 753 square miles. It accounts for 1.1% of the combined county land area in the state.
See the complete Wisconsin ranking · What counts as a county equivalent?
Population and density of Green County
The Census Bureau estimates that 37,227 people lived in Green County on July 1, 2025. That ranks #1,288 of 3,222 county equivalents nationally and #40 of 72 in Wisconsin. Since the April 1, 2020 estimates base of 37,090, the population has grown by 137 (+0.4%), compared with +1.3% for Wisconsin as a whole.
With 584 square miles of land, that is 64 people per square mile (25 per km²), placing Green County #1,339 nationally for density and #30 in Wisconsin. The median county equivalent has 47 people per square mile; the Wisconsin median is 51. Put another way, there are about 10 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 37,039 | 37,087 | 36,888 | 37,002 | 37,237 | 37,227 |
| Change | — | +48 | −199 | +114 | +235 | −10 |
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 Green County
Green County is divided into 24 cities and towns. In Wisconsin, county subdivisions are local governments, and together they cover all of the county’s land and residents.
The most populous is Monroe city, with 10,581 residents (28.4% of the county). The largest by land is Spring Grove town, at 39.8 mi², or 6.8% of the county’s land. Among those with at least 1,000 residents in 2020, Albany town grew fastest since then (+5.5%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Monroe cityCounty seat | 10,581 | −0.8% | 6.1 | 1% |
| Brodhead city | 3,129 | −1.8% | 1.654 | 0.3% |
| New Glarus village | 2,266 | 0% | 1.912 | 0.3% |
| Exeter town | 2,209 | +2.4% | 35.1 | 6% |
| Decatur town | 1,756 | +4% | 34.2 | 5.9% |
| New Glarus town | 1,427 | +2.4% | 34 | 5.8% |
| Monroe townCounty seat | 1,276 | −0.5% | 32.1 | 5.5% |
| Albany town | 1,241 | +5.5% | 34.3 | 5.9% |
| Monticello village | 1,173 | −1.3% | 1.194 | 0.2% |
| Jefferson town | 1,152 | −0.9% | 38.7 | 6.6% |
| Clarno town | 1,142 | +0.9% | 36.4 | 6.2% |
| Brooklyn town | 1,117 | +0.6% | 35.4 | 6.1% |
| Albany village | 1,089 | −2.1% | 1.27 | 0.2% |
| York town | 1,034 | +6.1% | 36.1 | 6.2% |
| Sylvester town | 1,007 | +0.1% | 35.2 | 6% |
Show the other 9 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Spring Grove town | 918 | −0.2% | 39.8 |
| Washington town | 853 | +1.9% | 36 |
| Cadiz town | 738 | −1.2% | 36.4 |
| Mount Pleasant town | 634 | +1.8% | 34.3 |
| Jordan town | 605 | +0.3% | 36 |
| Belleville village | 593 | +2.8% | 0.239 |
| Adams town | 545 | +0.9% | 36.1 |
| Brooklyn village | 500 | +0.4% | 0.565 |
| Browntown village | 242 | −0.4% | 1.054 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Green County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Green County is an outlying county of the Madison, WI Metropolitan Statistical Area. Its 4 county equivalents have 709,685 residents on 3,308.8 square miles of land; Green County accounts for 17.7% of the land and 5.2% of the residents. By combined land it ranks #90 of 393 metropolitan areas, and #87 by population. It belongs to the Madison-Janesville-Beloit, WI Combined Statistical Area.
| County equivalent | Population 2025 | Land mi² |
|---|---|---|
| Dane County | 590,375 | 1,196.5 |
| Columbia County | 58,132 | 765.6 |
| Green County | 37,227 | 584 |
| Iowa County | 23,951 | 762.7 |
ZIP codes
12 ZIP Code Tabulation Areas have land in Green County; 7 of them have most of their land inside the county, and the others mainly cover neighboring areas.
535025350453508535165352053521535225355053566535705357253574
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 Green County
Green County shares a land border with 6 county equivalents, including 2 in Illinois. It has more land than 2 of them. The largest neighbor is Dane County (1,196.5 mi²) and the smallest is Winnebago County (513 mi²). Together with its neighbors, Green County forms a block of 4,972.3 mi² of land, of which it holds 11.7%.
| Bordering county equivalent | Land mi² | Size vs. Green | Compare |
|---|---|---|---|
| Dane County | 1,196.5 | 2× larger | Compare |
| Iowa County | 762.7 | 1.3× larger | Compare |
| Rock County | 718.2 | 1.2× larger | Compare |
| Lafayette County | 633.6 | 1.1× larger | Compare |
| Stephenson CountyIllinois | 564.2 | about the same | Compare |
| Winnebago CountyIllinois | 513 | 1.1× smaller | Compare |
How big is Green County compared with U.S. states?
Green County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.8 times as much. Wisconsin’s county land could hold about 93 areas the size of Green County.
Another way to picture it: the same land area would fill a square about 24.2 miles (38.9 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 Green County?
Green County has more land than 1,538 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 Green County at #1,805 nationally by total area, 121 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 0.1%, compared with a national county-equivalent median of 1.2% — 1.1 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 Green County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1683 | Washington County, Florida | 584.7 | Compare |
| #1684 | Green County, Wisconsin | 584 | This county |
| #1685 | Adams County, Ohio | 583.9 | 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 42.675522, -89.605074. 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: 1,512,667,180 m²; AWATER: 1,313,240 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 Green County?
Green County, Wisconsin has 584 square miles (1,512.7 km²) of land and 0.507 square miles of water, for a total area of 584.6 square miles. It ranks #1684 of 3,222 U.S. county equivalents by land area.
Is Green County the largest county in Wisconsin?
No. Green County ranks #50 of 72 in Wisconsin by land area. The largest is Marathon County, with 1,545.2 square miles of land.
What counties border Green County?
Green County shares a land border with Rock County, Dane County, Stephenson County, Illinois, Lafayette County, Iowa County, and Winnebago County, Illinois.
What is the population of Green County?
The Census Bureau estimates Green County had 37,227 residents on July 1, 2025, ranking #1,288 of 3,222 county equivalents. That is 64 people per square mile of land.
What is the county seat of Green County?
The county seat of Green County is Monroe.
What cities and towns are in Green County?
Green County has 24 county subdivisions (cities, towns and townships). The most populous five are Monroe city, Brodhead city, New Glarus village, Exeter town, and Decatur town.
Is Green County part of a metropolitan area?
Yes. It is an outlying county of the Madison, WI Metropolitan Statistical Area, which has 4 county equivalents and 709,685 residents.
How many ZIP codes are in Green County?
12 ZIP Code Tabulation Areas have land in Green County, and 7 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Green County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.8 times as much land.
How many acres of land are in Green County?
The land measurement converts to approximately 373,788 acres. Including water, total area is approximately 374,113 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.