County outline
Where Winneshiek County is located
Area breakdown
Land accounts for 100% of Winneshiek County’s measured area and water for 0%. Its combined area converts to 1,787.4 square kilometers or approximately 441,684 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 689.844 | 1,786.688 | 441,500.2 |
| Water | 0.288 | 0.746 | 184.3 |
| Total | 690.132 | 1,787.434 | 441,684.5 |
How Winneshiek County compares
By original Census land area, Winneshiek County ranks #17 of 99 in Iowa and #1358 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.211 times the Iowa county-equivalent median of 569.6 square miles. It accounts for 1.2% of the combined county land area in the state.
See the complete Iowa ranking · What counts as a county equivalent?
Population and density of Winneshiek County
The Census Bureau estimates that 19,733 people lived in Winneshiek County on July 1, 2025. That ranks #1,898 of 3,222 county equivalents nationally and #33 of 99 in Iowa. Since the April 1, 2020 estimates base of 20,065, the population has declined by 332 (−1.7%), compared with +1.5% for Iowa as a whole.
With 689.8 square miles of land, that is 29 people per square mile (11 per km²), placing Winneshiek County #2,044 nationally for density and #44 in Iowa. The median county equivalent has 47 people per square mile; the Iowa median is 26. Put another way, there are about 22 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 20,046 | 19,943 | 19,907 | 19,703 | 19,673 | 19,733 |
| Change | — | −103 | −36 | −204 | −30 | +60 |
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 Winneshiek County
8 incorporated places lie at least partly in Winneshiek County. Together they are home to 10,408 people (52.7%); the other 9,325 (47.3%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Decorah city, with 7,417 residents in the county.
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Decorah cityCounty seat | 7,417 | −2.3% | 7.243 |
| Calmar city | 1,098 | −2.8% | 1.123 |
| Ossian city | 775 | −3.4% | 1.068 |
| Spillville city | 369 | −4.2% | 0.439 |
| Fort Atkinson city | 301 | −2.6% | 0.318 |
| Ridgeway city | 267 | −3.3% | 0.755 |
| Castalia city | 142 | −2.1% | 0.578 |
| Jackson Junction city | 39 | +5.4% | 5.957 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Winneshiek County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Winneshiek 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
12 ZIP Code Tabulation Areas have land in Winneshiek County; 7 of them have most of their land inside the county, and the others mainly cover neighboring areas.
521015213252133521365214052144521615216252165521685217152172
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 Winneshiek County
Winneshiek County shares a land border with 6 county equivalents, including 2 in Minnesota. It has more land than 4 of them. The largest neighbor is Fillmore County (861.3 mi²) and the smallest is Howard County (473.2 mi²). Together with its neighbors, Winneshiek County forms a block of 4,450.8 mi² of land, of which it holds 15.5%.
| Bordering county equivalent | Land mi² | Size vs. Winneshiek | Compare |
|---|---|---|---|
| Fillmore CountyMinnesota | 861.3 | 1.2× larger | Compare |
| Fayette County | 730.8 | 1.1× larger | Compare |
| Allamakee County | 639.1 | 1.1× smaller | Compare |
| Houston CountyMinnesota | 552.1 | 1.2× smaller | Compare |
| Chickasaw County | 504.3 | 1.4× smaller | Compare |
| Howard County | 473.2 | 1.5× smaller | Compare |
How big is Winneshiek County compared with U.S. states?
Winneshiek 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. Iowa’s county land could hold about 81 areas the size of Winneshiek County.
Another way to picture it: the same land area would fill a square about 26.3 miles (42.3 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 Winneshiek County?
Winneshiek County has more land than 1,864 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 Winneshiek County at #1,465 nationally by total area, 107 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%, 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 Winneshiek County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1357 | Phillips County, Arkansas | 690.4 | Compare |
| #1358 | Winneshiek County, Iowa | 689.8 | This county |
| #1359 | Ross County, Ohio | 689.2 | 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 43.292989, -91.850788. 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: 1,786,686,752 m²; AWATER: 745,729 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 Winneshiek County?
Winneshiek County, Iowa has 689.8 square miles (1,786.7 km²) of land and 0.288 square miles of water, for a total area of 690.1 square miles. It ranks #1358 of 3,222 U.S. county equivalents by land area.
Is Winneshiek County the largest county in Iowa?
No. Winneshiek County ranks #17 of 99 in Iowa by land area. The largest is Kossuth County, with 972.7 square miles of land.
What counties border Winneshiek County?
Winneshiek County shares a land border with Allamakee County, Fayette County, Howard County, Fillmore County, Minnesota, Chickasaw County, and Houston County, Minnesota.
What is the population of Winneshiek County?
The Census Bureau estimates Winneshiek County had 19,733 residents on July 1, 2025, ranking #1,898 of 3,222 county equivalents. That is 29 people per square mile of land.
What is the county seat of Winneshiek County?
The county seat of Winneshiek County is Decorah.
What cities and towns are in Winneshiek County?
Winneshiek County has 8 incorporated places. The most populous five are Decorah city, Calmar city, Ossian city, Spillville city, and Fort Atkinson city; 9,325 residents live outside any incorporated place.
Is Winneshiek County part of a metropolitan area?
No. Winneshiek County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Winneshiek County?
12 ZIP Code Tabulation Areas have land in Winneshiek 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 Winneshiek 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 Winneshiek County?
The land measurement converts to approximately 441,500 acres. Including water, total area is approximately 441,684 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.