| ZIP Codes: | 2 ZIP Codes (2 Standard, 0 PO Box, 0 Unique) [See All] |
| Area Code: | 605 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 11:55:03 PM |
| Population: | 1,080 [See All] |
| FIPS: | 46119 |
| CBSA: | Sioux Falls, SD-MN |
| Land Area: | 618 sq mi |
| Water Area: | 4 sq mi |
| Coordinates: | 44.7835, -100.1544 |
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1,080 residents live across 2 ZIPs covering 618 sq mi, served by 2 distinct USPS-recognized cities.
Population moved from 1,180 to 1,080 from 2014 to 2024 — a -8.5% change. 0 ZIPs gained residents, 2 lost.
The county's wealthiest ZIP 57564 (Onida, $74,297 median) and poorest ZIP 57520 (Agar, $50,417) are 14.2 miles apart — a 1.5× income gap across local geography.
Median home values vary 1.8× across this county — from $118,800 in 57520 (Agar) to $210,600 in 57564 (Onida).
Educational attainment ranges from 26.7% bachelor's+ in 57564 (Onida) to 34.0% in 57520 (Agar) — the breadth of educational profiles across the area.
Within South Dakota, this is the #74 most populous of 82 counties and ranks #68 for median household income .
Weighted by population, the typical household earns about $71,688 across the county — reflecting what a typical resident sees, not a simple ZIP average.
27.7% of adults age 25+ hold a bachelor's degree or higher (207 of 748 reporting).
2 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.
One ZIP holds the majority of this county's population — a sign of a county built around a single city or town.
Sully County lost 8.5% of residents between 2014 and 2024.