Sioux County is a county in Iowa, United States, in the northwest corner of the state along the South Dakota border. It had a population of 35,872 at the 2020 census and covers 768 square miles (1,989 km2) centred near 43°05′N 96°11′W.
Orange City is the county seat, and its postal code is 51041. The county has 13 incorporated cities, 13 unincorporated communities, and 24 civil townships. Sioux County lies in the Central time zone.
Towns & Villages in Sioux County
Sioux County has 13 incorporated cities and 13 smaller unincorporated communities, several of them mobile-home parks and rural crossroads. Iowa law classifies every incorporated municipality as a “city” regardless of size, so a place of under 100 residents can hold the same legal status as Sioux Center. In the table, “CDP” marks a census-designated place and “Unincorp.” marks a community with no municipal government.
| Place | Type | Pop. | ZIP |
|---|---|---|---|
| Orange City | City · seat | 6,267 | 51041 |
| Sioux Center | City | 8,229 | 51250 |
| Rock Valley | City | 4,059 | 51247 |
| Hawarden | City | 2,700 | 51023 |
| Hull | City | 2,384 | 51239 |
| Alton | City | 1,248 | 51003 |
| Hospers | City | 718 | 51238 |
| Boyden | City | 701 | 51234 |
| Ireton | City | 590 | 51027 |
| Granville | City | 310 | 51022 |
| Maurice | City | 265 | 51036 |
| Chatsworth | City | 75 | — |
| Matlock | City | 74 | — |
| Candlelight Village MH Park | Unincorp. | — | — |
| Carmel | Unincorp. | — | — |
| Carnes | Unincorp. | — | — |
| Elm Spring | Unincorp. | — | — |
| Highland Park | Unincorp. | — | — |
| Lebanon | Unincorp. | — | — |
| McNally | Unincorp. | — | — |
| Middleburg | Unincorp. | — | — |
| Newkirk | Unincorp. | — | — |
| Perkins | Unincorp. | — | — |
| Sunrise MH Park | Unincorp. | — | — |
| Twilight Trailer Court | Unincorp. | — | — |
| Westbrook Village | Unincorp. | — | — |
A place called “Sheldon” appears in older directories of Sioux County, but the only incorporated city of that name in Iowa sits in neighboring O’Brien County; it is not repeated here.
Townships
Sioux County is divided into 24 civil townships: Buncombe, Capel, Center, Eagle, East Orange, Floyd, Garfield, Grant, Holland, Lincoln, Logan, Lynn, Nassau, Plato, Reading, Rock, Settlers, Sheridan, Sherman, Sioux, Washington, Welcome, and West Branch. Per-township 2020 population is not published at this resolution, so populations are omitted rather than estimated.
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| East Orange | — | Orange City |
| Buncombe | — | — |
| Capel | — | — |
| Center | — | — |
| Eagle | — | — |
| Floyd | — | — |
| Garfield | — | — |
| Grant | — | — |
| Holland | — | — |
| Lincoln | — | — |
| Logan | — | — |
| Lynn | — | — |
| Nassau | — | — |
| Plato | — | — |
| Reading | — | — |
| Rock | — | — |
| Settlers | — | — |
| Sheridan | — | — |
| Sherman | — | — |
| Sioux | — | — |
| Washington | — | — |
| Welcome | — | — |
| West Branch | — | — |
ZIP Codes
- 51041 — Orange City
- 51250 — Sioux Center
- 51247 — Rock Valley
- 51023 — Hawarden
- 51239 — Hull
- 51003 — Alton
- 51238 — Hospers
- 51234 — Boyden
- 51027 — Ireton
- 51022 — Granville
- 51036 — Maurice
Chatsworth, Matlock, and the county’s unincorporated communities are served by the ZIP code of the nearest post-office town rather than a ZIP of their own.
Geography
Sioux County sits on the rolling Iowan Surface plain of the Missouri River basin, with the flatter Des Moines Lobe terrain to the east. The Big Sioux River forms part of the western county line, the Rock River drains the southwest, and the Floyd River rises in the eastern townships. The land is almost entirely cropland, with 768 square miles of land against just 1 square mile of water.
Sioux County borders Lincoln County, South Dakota to the northwest, Lyon County to the north, O’Brien County to the east, Plymouth County to the south, and Union County, South Dakota to the southwest. O’Brien County and Plymouth County (Iowa) do not currently have their own live pages on this site.
Demographics
Sioux County had 35,872 residents at the 2020 census, giving a density of about 47 people per square mile. Sioux Center (8,229) and Orange City (6,267) are the two largest communities and together hold more than 40% of the county’s population. The county has a strong Dutch-American identity: 2020 census figures put Dutch ancestry at roughly 40% of residents, the highest share of any county in Iowa. Household income here runs well above the Iowa median of $71,433, reflecting the county’s low unemployment and diversified farm-and-manufacturing economy.
Economy & Local Life
Agriculture anchors the county — corn, soybeans, hogs, and cattle — alongside food and agribusiness manufacturing clustered around Sioux Center and Orange City. Northwestern College in Orange City and Dordt University in Sioux Center are both four-year liberal-arts schools with enrollments above 1,000 students and are among the county’s largest employers. Sioux Center is also a regional retail and healthcare hub for northwest Iowa.
History
Sioux County was formed on January 15, 1851, and organized as a functioning county government on January 20, 1860. It takes its name from the Sioux people, who inhabited the region before white settlement. A wave of Dutch immigrants arrived beginning in 1869, founding Orange City and shaping the county’s churches, schools, and surnames to this day. The red sandstone Sioux County Courthouse in Orange City, completed in 1904, remains in use.
Getting There
U.S. Routes 18 and 75 and Iowa Highways 10, 12, and 60 cross the county.
- Sioux City, Iowa — 35 miles south
- Sioux Falls, South Dakota — 40 miles northwest
- Le Mars, Iowa — 25 miles southeast
- Spirit Lake, Iowa — 45 miles east
The nearest commercial airport is Sioux Gateway Airport in Sioux City; Sioux Falls Regional Airport is a larger alternative to the northwest.
Frequently Asked Questions
Where is Sioux County, Iowa?
It sits in the northwest corner of Iowa, on the South Dakota border, roughly 35 miles north of Sioux City.
What is the population of Sioux County?
35,872 residents at the 2020 census.
How big is Sioux County?
768 square miles (1,989 km2) of land and water.
What is the county seat of Sioux County?
Orange City is the county seat.
How many towns are in Sioux County?
13 incorporated cities, the largest being Sioux Center and Orange City, plus about 13 smaller unincorporated communities.
What ZIP codes are in Sioux County?
Major ZIPs include 51041 (Orange City), 51250 (Sioux Center), 51247 (Rock Valley), 51023 (Hawarden), and 51239 (Hull).
Why is Sioux County known for its Dutch heritage?
Dutch settlers began arriving in 1869 and founded Orange City; roughly 40% of residents still report Dutch ancestry, the highest share of any Iowa county.
More counties in this state: Towns and villages in Iowa.