Clay County is a county in Iowa, United States, anchored by the Little Sioux River in the northwest corner of the state. It had a population of 16,384 at the 2020 census and covers 573 square miles (1,480 km2) centred near 43°04′51″N 95°08′58″W.
Spencer is the county seat and its postal code is 51301. The county has 9 incorporated cities, several unincorporated communities and 16 civil townships. Clay County sits in the Central time zone.
Towns & Villages in Clay County
Clay County has 9 incorporated cities and a handful of unincorporated communities and mobile-home developments. Spencer, the county seat, is home to roughly seven in ten county residents; every other incorporated place has under 600 people. Unincorp. below means the place has never been formally incorporated.
| Place | Type | Township | Pop. | ZIP |
|---|---|---|---|---|
| Spencer | City · seat | — | 11,325 | 51301 |
| Everly | City | — | 576 | 51338 |
| Royal | City | — | 382 | 51357 |
| Peterson | City | Peterson | 324 | 51047 |
| Fostoria | City | — | 232 | 51340 |
| Dickens | City | — | 149 | 51333 |
| Webb | City | — | 142 | 51366 |
| Greenville | City | — | 69 | 51343 |
| Rossie | City | — | 48 | — |
| Gillett Grove | City | Gillett Grove | 32 | 51341 |
| Cornell | Unincorp. | — | — | — |
| Langdon | Unincorp. | — | — | — |
| Birchwood Estates | Unincorp. | — | — | — |
| Country Villa MH Park | Unincorp. | — | — | — |
Rossie has no post office of its own; mail there is handled through a neighboring ZIP. Birchwood Estates and Country Villa MH Park are manufactured-home developments near Spencer rather than platted towns, and their unofficial “township” assignment could not be verified, so it is left blank above.
Townships
Iowa still administers rural land through civil townships. Clay County has 16: Clay, Douglas, Freeman, Garfield, Gillett Grove, Herdland, Lake, Lincoln, Logan, Lone Tree, Meadow, Peterson, Riverton, Sioux, Summit and Waterford. Individual township population figures from the 2020 census were not verifiable at publication and are omitted rather than estimated.
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| Peterson | — | Peterson |
| Gillett Grove | — | Gillett Grove |
| Riverton | — | — |
| Summit | — | — |
| Logan | — | — |
| Meadow | — | — |
| Herdland | — | — |
| Waterford | — | — |
| Sioux | — | — |
| Lone Tree | — | — |
| Clay | — | — |
| Douglas | — | — |
| Freeman | — | — |
| Garfield | — | — |
| Lake | — | — |
| Lincoln | — | — |
ZIP Codes
- 51301 — Spencer (also serves the surrounding rural county and Rossie)
- 51338 — Everly
- 51357 — Royal
- 51047 — Peterson
- 51340 — Fostoria (PO box service only)
- 51333 — Dickens
- 51366 — Webb
- 51343 — Greenville
- 51341 — Gillett Grove (PO box service only)
Cornell, Langdon and the county’s rural addresses draw mail through the Spencer or Peterson post offices rather than a ZIP code of their own.
Geography
Clay County lies on rolling prairie shaped by glacial till, drained mainly by the Little Sioux River, which crosses the county from northeast to southwest. The Barringer Slough Wildlife Management Area, a large remnant wetland complex, sits in the county’s eastern townships and is a noted stop for migratory waterfowl. Farmland covers most of the remaining land, broken by scattered natural lakes and sloughs left behind by the last glaciation.
Clay County borders Dickinson County to the north, Palo Alto County to the east, Buena Vista County to the south, and O’Brien County to the west.
Demographics
Clay County had 16,384 residents at the 2020 census, spread across 567 square miles of land for a density of roughly 29 people per square mile. Spencer is by far the largest community at 11,325 residents, followed by Everly at 576. The county’s household income has not been independently verified for this profile; for context, the Iowa median is $71,433.
Economy & Local Life
Agriculture, particularly corn and soybean production and hog operations, remains the backbone of the county’s economy, supplemented by agribusiness and light manufacturing based in Spencer. Spencer also serves as the regional retail and medical hub for northwest Iowa, anchored by Spencer Hospital and a historic downtown rebuilt after a major 1931 fire. The Clay County Fair, held each September in Spencer, is one of the largest county fairs in the country and draws visitors from across the region.
History
Clay County was organized in the 1850s and named for Henry Clay Jr., a U.S. Army colonel killed at the Battle of Buena Vista during the Mexican-American War, and son of the Kentucky statesman Henry Clay. Spencer was platted along the Little Sioux River and grew as a rail and trade center for the surrounding farm townships. A downtown fire in June 1931 destroyed much of Spencer’s business district, and the rebuilt Art Deco storefronts that replaced it still define the city center today.
Getting There
U.S. Highways 18 and 71 and Iowa Highway 10 cross the county and meet at Spencer.
- Everly — southeast of Spencer
- Royal — southwest of Spencer
- Peterson — south of Spencer
- Webb — northeast of Spencer
Spencer Municipal Airport, three miles northwest of downtown Spencer, handles regional and general aviation; the nearest larger commercial airport is Sioux Gateway Airport in Sioux City.
Frequently Asked Questions
Where is Clay County, Iowa?
It is in the northwest corner of Iowa, bordering Dickinson County to the north and O’Brien County to the west.
What is the population of Clay County?
16,384 at the 2020 census.
How big is Clay County?
573 square miles (1,480 km2), of which 567 square miles are land.
What is the county seat of Clay County?
Spencer is the county seat.
How many towns are in Clay County?
Nine incorporated cities, plus several unincorporated communities.
What ZIP codes are in Clay County?
51301, 51333, 51338, 51340, 51341, 51343, 51357 and 51366.
What is Clay County known for?
The Clay County Fair in Spencer, one of the largest county fairs in the United States, and the Barringer Slough wetland complex.
More counties in this state: Towns and villages in Iowa.