| ZIP Codes: | 7 ZIP Codes (6 Standard, 1 PO Box, 0 Unique) [See All] |
| Area Code: | 605 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 2:13:43 PM |
| Population: | 6,053 [See All] |
| FIPS: | 46077 |
| Land Area: | 1,078 sq mi |
| Water Area: | 43 sq mi |
| Coordinates: | 44.3867, -97.4154 |
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6,053 residents live across 7 ZIPs covering 1,078 sq mi, served by 7 distinct USPS-recognized cities.
Population moved from 5,812 to 6,053 from 2014 to 2024 — a +4.1% change. 4 ZIPs gained residents, 3 lost.
The county's wealthiest ZIP 57212 (Arlington, $93,750 median) and poorest ZIP 57051 (Oldham, $56,250) are 15.4 miles apart — a 1.7× income gap across local geography.
Median home values vary 3.4× across this county — from $70,000 in 57214 (Badger) to $238,100 in 57212 (Arlington).
Density varies 35× across the county — from 2 people/sq mi in 57051 (Oldham) to 79 in 57214 (Badger).
Educational attainment ranges from 5.2% bachelor's+ in 57233 (Erwin) to 26.4% in 57051 (Oldham) — the breadth of educational profiles across the area.
Within South Dakota, this is the #29 most populous of 82 counties and ranks #46 for median household income .
Weighted by population, the typical household earns about $79,445 across the county — reflecting what a typical resident sees, not a simple ZIP average.
22.7% of adults age 25+ hold a bachelor's degree or higher (950 of 4,187 reporting).
6 Standard delivery, 1 PO Box only, 0 single-entity Unique ZIPs serve this county.
A frontier county — vast land area with only a few residents per square mile. Daily life looks very different here than in the country's denser counties.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 57212 | Arlington | Standard | 1,819 | $93,750 | 245.0 | -5.0% |
| 57231 | De Smet | Standard | 1,724 | $78,646 | 264.3 | -1.4% |
| 57249 | Lake Preston | Standard | 1,023 | $63,182 | 155.9 | 2.8% |
| 57353 | Iroquois | Standard | 812 | $75,625 | 299.1 | 16.7% |
| 57233 | Erwin | Standard | 350 | $82,917 | 38.1 | 117.4% |
| 57051 | Oldham | Standard | 163 | $56,250 | 73.2 | -33.7% |
| 57214 | Badger | PO Box | 162 | $65,000 | 2.1 | 224.0% |