Sioux County, Iowa
A county in Iowa, ranked 19 of 99 by population.
CountyFIPS 19167
- Population
- 36,774
- +886 (+2.5%) since 2020
- Land area
- 767.9
- square miles. A further 0.1% of the total area is water
- Population density
- 47.9
- people per square mile, computed rather than published
- County seat
- Orange City
- Seat of county government.
- Established
- 1851
- 174 years ago
- Largest city
- Sioux Center city
- Population 8,864.
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.
Satellite view
Aerial imagery of Sioux County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.
Where Sioux County ranks
Position among the 99 counties of Iowa, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.
| Measure | Value | In Iowa | Nationally |
|---|---|---|---|
| Population | 36,774 | 19th of 99 | 1,275th of 3,144 |
| Land area | 767.9 sq mi | 6th of 99 | 1,130th of 3,144 |
| Population density | 47.9 per sq mi | 23rd of 99 | 1,516th of 3,144 |
| Median household income | $86,098 | 8th of 99 | 401st of 3,143 |
Full data for Sioux County
| Measure | Value | Source and vintage |
|---|---|---|
| Population | 36,774 | Vintage 2025 Population Estimates |
| Population in 2020 | 35,888 | Vintage 2025 Population Estimates |
| 2020 estimates base? | 35,869 | Vintage 2025 Population Estimates |
| Land area | 767.9 sq mi | 2025 Gazetteer Files |
| Water area | 1.1 sq mi | 2025 Gazetteer Files |
| Total area | 769 sq mi | 2025 Gazetteer Files |
| Population density? | 47.9 per sq mi | Computed: Vintage 2025 estimates divided by 2025 Gazetteer land area |
| Median household income | $86,098 | American Community Survey 2020-2024 5-Year Estimates |
| Median home value | $250,100 | American Community Survey 2020-2024 5-Year Estimates |
| Median age | 33.8 | American Community Survey 2020-2024 5-Year Estimates |
| Households | 12,690 | American Community Survey 2020-2024 5-Year Estimates |
| Housing units | 13,285 | American Community Survey 2020-2024 5-Year Estimates |
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.
How the population changed
The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:
- Births minus deaths
- +191
- 460 births, 269 deaths
- Net migration
- -195
- More people moved out than moved in.
Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.
The 7 areas bordering Sioux County
Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.
| Bordering area | State | Shared border | Population |
|---|---|---|---|
| Lyon County | Iowa | 35 mi | 12,354 |
| Plymouth County | Iowa | 34 mi | 25,697 |
| O'Brien County | Iowa | 24 mi | 14,220 |
| Lincoln County | South Dakota | 23 mi | 77,145 |
| Union County | South Dakota | 21 mi | 17,402 |
| Cherokee County | Iowa | a single point | 11,369 |
| Osceola County | Iowa | a single point | 5,980 |
Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.
All 99 counties of Iowa
Open the interactive Iowa county map, or jump straight to any of them.
- Adair County
- Adams County
- Allamakee County
- Appanoose County
- Audubon County
- Benton County
- Black Hawk County
- Boone County
- Bremer County
- Buchanan County
- Buena Vista County
- Butler County
- Calhoun County
- Carroll County
- Cass County
- Cedar County
- Cerro Gordo County
- Cherokee County
- Chickasaw County
- Clarke County
- Clay County
- Clayton County
- Clinton County
- Crawford County
- Dallas County
- Davis County
- Decatur County
- Delaware County
- Des Moines County
- Dickinson County
- Dubuque County
- Emmet County
- Fayette County
- Floyd County
- Franklin County
- Fremont County
- Greene County
- Grundy County
- Guthrie County
- Hamilton County
- Hancock County
- Hardin County
- Harrison County
- Henry County
- Howard County
- Humboldt County
- Ida County
- Iowa County
- Jackson County
- Jasper County
- Jefferson County
- Johnson County
- Jones County
- Keokuk County
- Kossuth County
- Lee County
- Linn County
- Louisa County
- Lucas County
- Lyon County
- Madison County
- Mahaska County
- Marion County
- Marshall County
- Mills County
- Mitchell County
- Monona County
- Monroe County
- Montgomery County
- Muscatine County
- O'Brien County
- Osceola County
- Page County
- Palo Alto County
- Plymouth County
- Pocahontas County
- Polk County
- Pottawattamie County
- Poweshiek County
- Ringgold County
- Sac County
- Scott County
- Shelby County
- Sioux County
- Story County
- Tama County
- Taylor County
- Union County
- Van Buren County
- Wapello County
- Warren County
- Washington County
- Wayne County
- Webster County
- Winnebago County
- Winneshiek County
- Woodbury County
- Worth County
- Wright County
Data on this page last rebuilt 30 August 2026. How these figures are produced.