County outline
Where Wapello County is located
Area breakdown
Land accounts for 99% of Wapello County’s measured area and water for 1%. Its combined area converts to 1,129.3 square kilometers or approximately 279,053 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 431.848 | 1,118.481 | 276,382.7 |
| Water | 4.173 | 10.808 | 2,670.7 |
| Total | 436.021 | 1,129.289 | 279,053.4 |
How Wapello County compares
By original Census land area, Wapello County ranks #86 of 99 in Iowa and #2348 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.758 times the Iowa county-equivalent median of 569.6 square miles. It accounts for 0.8% of the combined county land area in the state.
See the complete Iowa ranking · What counts as a county equivalent?
Population and density of Wapello County
The Census Bureau estimates that 35,210 people lived in Wapello County on July 1, 2025. That ranks #1,339 of 3,222 county equivalents nationally and #20 of 99 in Iowa. Since the April 1, 2020 estimates base of 35,442, the population has declined by 232 (−0.7%), compared with +1.5% for Iowa as a whole.
With 431.8 square miles of land, that is 82 people per square mile (31 per km²), placing Wapello County #1,143 nationally for density and #14 in Iowa. The median county equivalent has 47 people per square mile; the Iowa median is 26. Put another way, there are about 7.8 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 35,334 | 35,308 | 35,082 | 35,379 | 35,429 | 35,210 |
| Change | — | −26 | −226 | +297 | +50 | −219 |
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 Wapello County
7 incorporated places lie at least partly in Wapello County. Together they are home to 27,928 people (79.3%); the other 7,282 (20.7%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Ottumwa city, with 25,319 residents in the county.
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Ottumwa cityCounty seat | 25,319 | −0.9% | 16.1 |
| Eldon city | 776 | −1.5% | 1.094 |
| Eddyville cityAlso in 2 other counties | 724 | −1.1% | 1.148 |
| Agency city | 612 | −0.8% | 0.566 |
| Blakesburg city | 263 | −1.9% | 0.271 |
| Kirkville city | 159 | +1.9% | 0.563 |
| Chillicothe city | 75 | −1.3% | 0.226 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Wapello County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Wapello County is a central county of the Ottumwa, IA Micropolitan Statistical Area. Wapello County is the area’s only county equivalent, so the micro area has the same 431.8 square miles of land. By combined land it ranks #462 of 542 micropolitan areas, and #388 by population.
ZIP codes
12 ZIP Code Tabulation Areas have land in Wapello County; 6 of them have most of their land inside the county, and the others mainly cover neighboring areas.
525015253052531525335253652537525485255252553525545256352566
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 Wapello County
Wapello County shares a land border with 5 county equivalents. Each of them has more land than Wapello County. The largest neighbor is Keokuk County (579.2 mi²) and the smallest is Monroe County (433.7 mi²). Together with its neighbors, Wapello County forms a block of 2,953.3 mi² of land, of which it holds 14.6%.
| Bordering county equivalent | Land mi² | Size vs. Wapello | Compare |
|---|---|---|---|
| Keokuk County | 579.2 | 1.3× larger | Compare |
| Mahaska County | 570.9 | 1.3× larger | Compare |
| Davis County | 502.2 | 1.2× larger | Compare |
| Jefferson County | 435.5 | about the same | Compare |
| Monroe County | 433.7 | about the same | Compare |
How big is Wapello County compared with U.S. states?
Wapello County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.4 times as much. Iowa’s county land could hold about 129 areas the size of Wapello County.
Another way to picture it: the same land area would fill a square about 20.8 miles (33.4 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 Wapello County?
Wapello County has more land than 874 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 Wapello County at #2,409 nationally by total area, 61 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 1%, compared with a national county-equivalent median of 1.2% — 0.2 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 Wapello County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2347 | Red Lake County, Minnesota | 432.4 | Compare |
| #2348 | Wapello County, Iowa | 431.8 | This county |
| #2349 | Douglas County, South Dakota | 431.8 | 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 41.031728, -92.409469. 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: 1,118,480,950 m²; AWATER: 10,808,726 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 Wapello County?
Wapello County, Iowa has 431.8 square miles (1,118.5 km²) of land and 4.173 square miles of water, for a total area of 436 square miles. It ranks #2348 of 3,222 U.S. county equivalents by land area.
Is Wapello County the largest county in Iowa?
No. Wapello County ranks #86 of 99 in Iowa by land area. The largest is Kossuth County, with 972.7 square miles of land.
What counties border Wapello County?
Wapello County shares a land border with Davis County, Jefferson County, Monroe County, Keokuk County, and Mahaska County.
What is the population of Wapello County?
The Census Bureau estimates Wapello County had 35,210 residents on July 1, 2025, ranking #1,339 of 3,222 county equivalents. That is 82 people per square mile of land.
What is the county seat of Wapello County?
The county seat of Wapello County is Ottumwa.
What cities and towns are in Wapello County?
Wapello County has 7 incorporated places. The most populous five are Ottumwa city, Eldon city, Eddyville city, Agency city, and Blakesburg city; 7,282 residents live outside any incorporated place.
Is Wapello County part of a metropolitan area?
Yes. It is a central county of the Ottumwa, IA Micropolitan Statistical Area.
How many ZIP codes are in Wapello County?
12 ZIP Code Tabulation Areas have land in Wapello County, and 6 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Wapello County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2.4 times as much land.
How many acres of land are in Wapello County?
The land measurement converts to approximately 276,383 acres. Including water, total area is approximately 279,053 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.