Monona County is a county in Iowa, United States, on the Missouri River bluffs along the Nebraska line. It had a population of 8,751 at the 2020 census and covers 699 square miles (1,810 km2) centred near 42°02′50″N 95°58′07″W.
Onawa is the county seat, and its postal code is 51040. The county has 10 incorporated cities and towns, 4 unincorporated communities, and 19 civil townships. It sits in the Central time zone and carries FIPS county code 67.
Towns & Villages in Monona County
Monona County has 10 incorporated places and 4 unincorporated communities. Onawa is the only city over 2,000 people; the rest are small towns strung along U.S. Route 75 and the county’s rail lines. CDP = census-designated place; Unincorp. = unincorporated community with no municipal government.
| Place | Type | Pop. | ZIP |
|---|---|---|---|
| Onawa | City · seat | 2,906 | 51040 |
| Mapleton | City | 1,165 | 51034 |
| Whiting | City | 745 | 51063 |
| Ute | City | 338 | 51060 |
| Blencoe | City | 233 | 51523 |
| Moorhead | City | 199 | 51558 |
| Soldier | City | 184 | 51572 |
| Castana | City | 107 | 51010 |
| Turin | City | 72 | — |
| Rodney | City | 45 | 51051 |
| Albaton | Unincorp. | — | — |
| Kennebec | Unincorp. | — | — |
| Preparation | Unincorp. | — | — |
| Ticonic | Unincorp. | — | — |
Townships
Monona County is divided into 19 civil townships, which handle rural road maintenance and cemetery upkeep rather than municipal services. Reliable 2020 population figures broken out by township are not published; the table below lists each township by name only.
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| Ashton | — | — |
| Belvidere | — | — |
| Center | — | — |
| Cooper | — | — |
| Fairview | — | — |
| Franklin | — | — |
| Grant | — | — |
| Jordan | — | — |
| Kennebec | — | Kennebec |
| Lake | — | — |
| Lincoln | — | — |
| Maple | — | — |
| St. Clair | — | — |
| Sherman | — | — |
| Sioux | — | — |
| Soldier | — | Soldier |
| Spring Valley | — | — |
| West Fork | — | — |
| Willow | — | — |
ZIP Codes
- 51040 — Onawa (also serves the county’s Missouri River bottomlands)
- 51034 — Mapleton
- 51063 — Whiting
- 51060 — Ute
- 51523 — Blencoe
- 51558 — Moorhead
- 51572 — Soldier
- 51010 — Castana
- 51051 — Rodney
Turin and the unincorporated communities of Albaton, Kennebec, Preparation, and Ticonic have no ZIP code of their own and are served by the nearest listed post office town.
Geography
Monona County lies in the Loess Hills, a narrow belt of wind-deposited silt ridges running along the east side of the Missouri River valley. The Missouri itself forms the county’s western edge, with the Little Sioux River cutting through the eastern townships before joining it. Bottomland along the river is flat farm ground; the hills rise sharply just east of it, giving the county some of Iowa’s steepest terrain outside the Loess Hills State Forest, which occupies part of the southwest.
Monona County borders Woodbury County to the north, Crawford County to the east, Harrison County to the south, and Burt and Thurston counties in Nebraska across the river to the southwest and west.
Demographics
The 2020 census counted 8,751 residents, a density of about 12.6 people per square mile. Onawa (2,906) and Mapleton (1,165) are the two largest communities and together hold roughly 47 percent of the county’s population. Median household income runs below the Iowa median of $71,433, typical of a farm-dependent western Iowa county with a shrinking, aging population base.
Economy & Local Life
Row-crop and livestock farming — corn, soybeans, and cattle — drives the county economy, supplemented by grain elevators, farm-implement dealers, and small manufacturing in Onawa and Mapleton. Onawa’s Monona County Memorial Hospital and the Whiting-based school district are among the larger local employers. The Monona County Fair, held each summer in Onawa, is the county’s biggest annual gathering.
History
Monona County was organized in 1851. Its name is generally traced to a Native American word meaning “beautiful valley,” a name shared with counties and places in Wisconsin and elsewhere in the country. The county’s most notable episode of destruction came from the Missouri River itself: repeated 19th- and 20th-century flooding and channel shifts forced Onawa to relocate its original townsite, and the river’s meandering course still defines the county’s western boundary disputes with Nebraska.
Getting There
U.S. Route 75 runs north–south through the county along the Loess Hills, connecting Onawa to Sioux City and Omaha; Iowa Highway 175 crosses east–west through Onawa and Mapleton toward the interior of the state.
- Sioux City, Iowa — 30 miles north
- Omaha, Nebraska — 75 miles south
- Denison, Iowa — 30 miles east
- Sioux Falls, South Dakota — 95 miles north
The nearest commercial airport is Sioux Gateway Airport in Sioux City.
Frequently Asked Questions
Where is Monona County?
It is in western Iowa, along the Missouri River and the Nebraska state line, in the Loess Hills.
What is the population of Monona County?
8,751 at the 2020 census.
How big is Monona County?
699 square miles (1,810 km2), of which 694 square miles is land.
What is the county seat of Monona County?
Onawa is the county seat.
How many towns are in Monona County?
10 incorporated cities and towns plus 4 unincorporated communities.
What ZIP codes are in Monona County?
Nine ZIP codes, from 51010 (Castana) to 51572 (Soldier); see the ZIP Codes section above.
What river runs through Monona County?
The Missouri River forms its western border, with the Little Sioux River crossing the eastern townships.
More counties in this state: Towns and villages in Iowa.