| ZIP Codes: | 5 ZIP Codes (5 Standard, 0 PO Box, 0 Unique) [See All] |
| Area Code: | 605 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 2:13:44 PM |
| Population: | 18,252 [See All] |
| FIPS: | 46127 |
| CBSA: | Sioux City, IA-NE-SD |
| Land Area: | 583 sq mi |
| Water Area: | 6 sq mi |
| Coordinates: | 42.7750, -96.6467 |
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18,252 residents live across 5 ZIPs covering 583 sq mi, served by 5 distinct USPS-recognized cities.
Population moved from 15,762 to 18,252 from 2014 to 2024 — a +15.8% change. 4 ZIPs gained residents, 1 lost.
The county's wealthiest ZIP 57038 (Jefferson, $106,250 median) and poorest ZIP 57001 (Alcester, $69,531) are 26.8 miles apart — a 1.5× income gap across local geography.
Median home values vary 2.4× across this county — from $177,400 in 57001 (Alcester) to $432,100 in 57049 (North Sioux City).
Density varies 53× across the county — from 10 people/sq mi in 57001 (Alcester) to 509 in 57049 (North Sioux City).
Educational attainment ranges from 24.4% bachelor's+ in 57001 (Alcester) to 44.1% in 57049 (North Sioux City) — the breadth of educational profiles across the area.
Within South Dakota, this is the #12 most populous of 82 counties and ranks #11 for median household income with the #8 fastest decade growth .
Weighted by population, the typical household earns about $91,804 across the county — reflecting what a typical resident sees, not a simple ZIP average.
36.3% of adults age 25+ hold a bachelor's degree or higher (4,546 of 12,517 reporting).
5 Standard delivery, 0 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.