County outline
Where Columbia County is located
Area breakdown
Land accounts for 96.2% of Columbia County’s measured area and water for 3.8%. Its combined area converts to 2,061.6 square kilometers or approximately 509,430 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 765.6 | 1,982.895 | 489,984 |
| Water | 30.385 | 78.697 | 19,446.4 |
| Total | 795.985 | 2,061.592 | 509,430.4 |
How Columbia County compares
By original Census land area, Columbia County ranks #34 of 72 in Wisconsin and #1136 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.017 times the Wisconsin county-equivalent median of 753 square miles. It accounts for 1.4% of the combined county land area in the state.
See the complete Wisconsin ranking · What counts as a county equivalent?
Population and density of Columbia County
The Census Bureau estimates that 58,132 people lived in Columbia County on July 1, 2025. That ranks #927 of 3,222 county equivalents nationally and #26 of 72 in Wisconsin. Since the April 1, 2020 estimates base of 58,494, the population has declined by 362 (−0.6%), compared with +1.3% for Wisconsin as a whole.
With 765.6 square miles of land, that is 76 people per square mile (29 per km²), placing Columbia County #1,201 nationally for density and #26 in Wisconsin. The median county equivalent has 47 people per square mile; the Wisconsin median is 51. Put another way, there are about 8.4 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 58,534 | 58,455 | 58,383 | 57,941 | 58,005 | 58,132 |
| Change | — | −79 | −72 | −442 | +64 | +127 |
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 Columbia County
Columbia County is divided into 35 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 Portage city, with 9,956 residents (17.1% of the county). The largest by land is Caledonia town, at 57.7 mi², or 7.5% of the county’s land. Among those with at least 1,000 residents in 2020, Poynette village grew fastest since then (+12.4%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Portage cityCounty seat | 9,956 | −6% | 8.982 | 1.2% |
| Columbus city | 5,400 | −2.5% | 4.515 | 0.6% |
| Lodi town | 3,259 | −0.9% | 26.6 | 3.5% |
| Lodi city | 3,190 | 0% | 1.726 | 0.2% |
| Poynette village | 2,924 | +12.4% | 2.569 | 0.3% |
| Pacific town | 2,769 | −0.5% | 19.4 | 2.5% |
| Dekorra town | 2,485 | 0% | 40.4 | 5.3% |
| Wisconsin Dells city | 2,452 | +0% | 3.443 | 0.4% |
| Pardeeville village | 2,248 | +8.3% | 1.925 | 0.3% |
| West Point town | 2,066 | +2% | 28.6 | 3.7% |
| Fall River village | 1,853 | −0.1% | 1.889 | 0.2% |
| Wyocena town | 1,782 | +1.9% | 35.7 | 4.7% |
| Caledonia town | 1,489 | −0.5% | 57.7 | 7.5% |
| Lewiston town | 1,244 | −1% | 52.5 | 6.9% |
| Marcellon town | 1,141 | +0.2% | 35.1 | 4.6% |
Show the other 20 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Rio village | 1,123 | −0.2% | 1.254 |
| Lowville town | 1,018 | +0.2% | 34.8 |
| Scott town | 888 | +2.9% | 35.6 |
| Fountain Prairie town | 876 | −0.8% | 34 |
| Arlington village | 860 | +1.5% | 1.037 |
| Fort Winnebago town | 810 | −0.5% | 32.1 |
| Arlington town | 796 | −0.7% | 34.8 |
| Cambria village | 765 | −1% | 1.014 |
| Randolph town | 761 | −0.4% | 35 |
| Leeds town | 743 | −1.6% | 35.3 |
| Wyocena village | 733 | −3.4% | 1.434 |
| Otsego town | 656 | −1.5% | 30.4 |
| Columbus town | 625 | −0.2% | 31 |
| Newport town | 592 | −2.1% | 20.1 |
| Hampden town | 570 | −1.9% | 35.7 |
| Springvale town | 537 | −1.5% | 40.7 |
| Courtland town | 483 | −1.8% | 35.2 |
| Randolph village | 449 | −2.2% | 0.3 |
| Friesland village | 317 | 0% | 1.01 |
| Doylestown village | 272 | −2.2% | 3.883 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Columbia County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Columbia 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; Columbia County accounts for 23.1% of the land and 8.2% 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
20 ZIP Code Tabulation Areas have land in Columbia County; 13 of them have most of their land inside the county, and the others mainly cover neighboring areas.
5353253555535615357853583539015391153913539235392553926539285393253935539545395553956539605396553969
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 Columbia County
Columbia County shares a land border with 6 county equivalents. It has more land than 3 of them. The largest neighbor is Dane County (1,196.5 mi²) and the smallest is Green Lake County (349.5 mi²). Together with its neighbors, Columbia County forms a block of 5,120.3 mi² of land, of which it holds 15%.
| Bordering county equivalent | Land mi² | Size vs. Columbia | Compare |
|---|---|---|---|
| Dane County | 1,196.5 | 1.6× larger | Compare |
| Dodge County | 875.7 | 1.1× larger | Compare |
| Sauk County | 831.6 | 1.1× larger | Compare |
| Adams County | 645.6 | 1.2× smaller | Compare |
| Marquette County | 455.7 | 1.7× smaller | Compare |
| Green Lake County | 349.5 | 2.2× smaller | Compare |
How big is Columbia County compared with U.S. states?
Columbia County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.4 times as much. Wisconsin’s county land could hold about 71 areas the size of Columbia County.
Another way to picture it: the same land area would fill a square about 27.7 miles (44.5 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 Columbia County?
Columbia County has more land than 2,086 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 Columbia County at #1,190 nationally by total area, 54 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 3.8%, compared with a national county-equivalent median of 1.2% — 2.6 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 Columbia County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1135 | Columbia County, Arkansas | 766.1 | Compare |
| #1136 | Columbia County, Wisconsin | 765.6 | This county |
| #1137 | Falls County, Texas | 765.5 | 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 43.471882, -89.330472. 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: 1,982,893,731 m²; AWATER: 78,697,463 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 Columbia County?
Columbia County, Wisconsin has 765.6 square miles (1,982.9 km²) of land and 30.4 square miles of water, for a total area of 796 square miles. It ranks #1136 of 3,222 U.S. county equivalents by land area.
Is Columbia County the largest county in Wisconsin?
No. Columbia County ranks #34 of 72 in Wisconsin by land area. The largest is Marathon County, with 1,545.2 square miles of land.
What counties border Columbia County?
Columbia County shares a land border with Dane County, Sauk County, Dodge County, Marquette County, Green Lake County, and Adams County.
What is the population of Columbia County?
The Census Bureau estimates Columbia County had 58,132 residents on July 1, 2025, ranking #927 of 3,222 county equivalents. That is 76 people per square mile of land.
What is the county seat of Columbia County?
The county seat of Columbia County is Portage.
What cities and towns are in Columbia County?
Columbia County has 35 county subdivisions (cities, towns and townships). The most populous five are Portage city, Columbus city, Lodi town, Lodi city, and Poynette village.
Is Columbia 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 Columbia County?
20 ZIP Code Tabulation Areas have land in Columbia County, and 13 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Columbia County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.4 times as much land.
How many acres of land are in Columbia County?
The land measurement converts to approximately 489,984 acres. Including water, total area is approximately 509,430 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.