Osceola County is a county in Iowa, United States, in the northwest corner of the state along the Minnesota border. It had a population of 6,192 at the 2020 census and covers 399 square miles (1,034 km2) centred near 43°22′N 95°38′W.
Sibley is the county seat, and its postal code is 51249. The county has 5 incorporated cities, 3 unincorporated communities, and 12 civil townships. Osceola County sits in the Central time zone and carries FIPS county code 72. It is the smallest county in Iowa by land area and one of the last to be organized, in 1872.
Towns & Villages in Osceola County
Eight named places appear on maps of the county: five incorporated cities and three small unincorporated communities. Sibley, the county seat, holds nearly half of all county residents. CDP = census-designated place; Unincorp. = unincorporated community with no municipal government.
| Place | Type | Township | Pop. | ZIP |
|---|---|---|---|---|
| Sibley | City · seat | — | 2,860 | 51249 |
| Ocheyedan | City | Ocheyedan | 439 | 51354 |
| Ashton | City | — | 436 | 51232 |
| Melvin | City | — | 199 | 51350 |
| Harris | City | — | 151 | 51345 |
| Allendorf | Unincorp. | — | — | 51249 |
| Cloverdale | Unincorp. | — | — | 51249 |
| May City | Unincorp. | — | — | 51354 |
Townships
Osceola County is divided into 12 civil townships. The Census Bureau does not report separate 2020 population figures for Iowa’s minor civil divisions, so populations are omitted below rather than estimated.
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| Baker | — | — |
| Ocheyedan | — | Ocheyedan |
| Fairview | — | — |
| Wilson | — | — |
| Horton | — | — |
| Allison | — | — |
| East Holman | — | — |
| West Holman | — | — |
| Gilman | — | — |
| Goewey | — | — |
| Harrison | — | — |
| Viola | — | — |
ZIP Codes
- 51249 — Sibley (also serves Allendorf and Cloverdale)
- 51354 — Ocheyedan (also serves May City)
- 51232 — Ashton
- 51350 — Melvin
- 51345 — Harris
All eight named places in the county share these five delivery ZIPs; there are no PO-Box-only or single-entity codes here.
Geography
Osceola County lies on the rolling till plains of northwest Iowa’s Prairie Coteau region. The Ocheyedan River crosses the county’s east side, and Hawkeye Point, at 1,670 feet (509 m), sits along the north edge near the Minnesota line — the highest natural point in Iowa. Most of the county’s 399 square miles is farmland; only about 0.7 square miles is water.
The county borders Jackson County, Minnesota to the northeast and Nobles County, Minnesota to the northwest, Dickinson County, Iowa to the east, O’Brien County, Iowa to the south, and Lyon County, Iowa to the west.
Demographics
Osceola County had 6,192 residents at the 2020 census. Sibley, with 2,860 people, and Ocheyedan, with 439, are the two largest communities, together holding just over half the county’s population. Iowa’s 2023 median household income was the Iowa median of $71,433; county-level income here is not separately verified for this profile. With 399 square miles of land, the county’s overall density works out to roughly 15.5 people per square mile, well below the statewide average, typical of Iowa’s sparsely settled northwest corner.
Economy & Local Life
Agriculture drives the county economy — corn, soybeans, and livestock on the till-plain farmland that covers most of the county. Sibley functions as the county’s trade and service center, with the county’s schools, hospital, and main retail concentrated there. The Osceola County Fair, held in Sibley each summer, is the county’s best-known annual event.
History
Osceola County was created by the Iowa legislature on January 15, 1851, but was not organized with its own government until January 1, 1872, making it one of the last Iowa counties to organize. It is named for Osceola, the Seminole war leader who resisted removal from Florida in the 1830s. Sibley, the county seat, takes its name from Henry Hastings Sibley, a Minnesota territorial figure and the state’s first governor.
Getting There
U.S. Highway 59 runs north–south through Sibley, and Iowa Highways 9 and 60 cross the county east–west and northeast–southwest. Nearby cities by road:
- Spencer, Iowa — about 25 miles southeast
- Worthington, Minnesota — about 30 miles north
- Spirit Lake, Iowa — about 25 miles east
- Sioux Falls, South Dakota — about 55 miles west
The nearest commercial airport is Sioux Falls Regional Airport in South Dakota; the county has no scheduled Amtrak service.
Frequently Asked Questions
Where is Osceola County, Iowa?
It is in the northwest corner of Iowa, bordering Minnesota, about 55 miles east of Sioux Falls, South Dakota.
What is the population of Osceola County?
6,192 people at the 2020 census.
How big is Osceola County?
399 square miles (1,034 km2), the smallest county in Iowa by land area.
What is the county seat of Osceola County?
Sibley is the county seat.
How many towns are in Osceola County?
Five incorporated cities — Sibley, Ocheyedan, Ashton, Melvin, and Harris — plus three unincorporated communities.
What ZIP codes are in Osceola County?
51249 (Sibley), 51354 (Ocheyedan), 51232 (Ashton), 51350 (Melvin), and 51345 (Harris).
What is Iowa’s highest point, and is it here?
Yes — Hawkeye Point, at 1,670 feet (509 m), is in the northern part of Osceola County.
More counties in this state: Towns and villages in Iowa.