| ZIP Codes: | 7 ZIP Codes (5 Standard, 2 PO Box, 0 Unique) [See All] |
| Area Code: | 605 |
| Timezone: | Mountain (GMT -07:00) |
| Local Time: | 11:55:01 PM |
| Population: | 5,777 [See All] |
| FIPS: | 46041 |
| Land Area: | 2,983 sq mi |
| Water Area: | 96 sq mi |
| Coordinates: | 45.2557, -101.1050 |
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5,777 residents live across 7 ZIPs covering 2,983 sq mi, served by 7 distinct USPS-recognized cities.
Population moved from 6,280 to 5,777 from 2014 to 2024 — a -8.0% change. 3 ZIPs gained residents, 4 lost.
The county's wealthiest ZIP 57636 (Lantry, $112,375 median) and poorest ZIP 57652 (Ridgeview, $19,327) are 41.2 miles apart — a 5.8× income gap across local geography.
Median home values vary 1.6× across this county — from $68,000 in 57625 (Eagle Butte) to $108,800 in 57636 (Lantry).
Density varies 16× across the county — from 1 people/sq mi in 57652 (Ridgeview) to 8 in 57661 (Whitehorse).
Educational attainment ranges from 4.4% bachelor's+ in 57652 (Ridgeview) to 23.8% in 57656 (Timber Lake) — the breadth of educational profiles across the area.
Within South Dakota, this is the #32 most populous of 82 counties and ranks #67 for median household income .
Weighted by population, the typical household earns about $50,450 across the county — reflecting what a typical resident sees, not a simple ZIP average.
17.9% of adults age 25+ hold a bachelor's degree or higher (555 of 3,094 reporting).
5 Standard delivery, 2 PO Box only, 0 single-entity Unique ZIPs serve this county.
Median household income spans 5.8× between the wealthiest and poorest ZIPs — a sign of significant intra-county inequality.
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.
One ZIP holds the majority of this county's population — a sign of a county built around a single city or town.
Dewey County lost 8.0% of residents between 2014 and 2024. ZIPs that shed the largest share:
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 57625 | Eagle Butte | Standard | 3,775 | $43,235 | 1,200.4 | -15.5% |
| 57656 | Timber Lake | Standard | 1,000 | $66,094 | 419.8 | 46.2% |
| 57633 | Isabel | Standard | 445 | $78,750 | 606.2 | -0.4% |
| 57652 | Ridgeview | Standard | 265 | $19,327 | 512.5 | -42.4% |
| 57661 | Whitehorse | PO Box | 177 | $55,000 | 21.9 | 47.5% |
| 57636 | Lantry | PO Box | 104 | $112,375 | 56.9 | 79.3% |
| 57630 | Glencross | Standard | 11 | — | 165.7 | -76.1% |