| ZIP Codes: | 7 ZIP Codes (7 Standard, 0 PO Box, 0 Unique) [See All] |
| Area Code: | 605 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 11:55:02 PM |
| Population: | 11,128 [See All] |
| FIPS: | 46079 |
| Land Area: | 609 sq mi |
| Water Area: | 12 sq mi |
| Coordinates: | 44.0354, -97.0947 |
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11,128 residents live across 7 ZIPs covering 609 sq mi, served by 7 distinct USPS-recognized cities.
Population moved from 11,908 to 11,128 from 2014 to 2024 — a -6.6% change. 4 ZIPs gained residents, 3 lost.
The county's wealthiest ZIP 57076 (Winfred, $118,281 median) and poorest ZIP 57057 (Rutland, $71,500) are 20.8 miles apart — a 1.7× income gap across local geography.
Median home values vary 4.4× across this county — from $97,100 in 57054 (Ramona) to $426,800 in 57075 (Wentworth).
Density varies 13× across the county — from 3 people/sq mi in 57076 (Winfred) to 37 in 57042 (Madison).
Educational attainment ranges from 14.2% bachelor's+ in 57054 (Ramona) to 56.0% in 57050 (Nunda) — the breadth of educational profiles across the area.
Within South Dakota, this is the #17 most populous of 82 counties and ranks #7 for median household income .
Weighted by population, the typical household earns about $80,391 across the county — reflecting what a typical resident sees, not a simple ZIP average.
34.4% of adults age 25+ hold a bachelor's degree or higher (2,680 of 7,781 reporting).
7 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.
Lake County lost 6.6% of residents between 2014 and 2024. ZIPs that shed the largest share:
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 57042 | Madison | Standard | 7,756 | $71,868 | 209.5 | -15.1% |
| 57075 | Wentworth | Standard | 1,296 | $106,763 | 78.2 | 48.5% |
| 57054 | Ramona | Standard | 703 | $86,875 | 115.3 | 35.7% |
| 57016 | Chester | Standard | 676 | $95,815 | 28.2 | -5.2% |
| 57076 | Winfred | Standard | 325 | $118,281 | 112.4 | 2.8% |
| 57057 | Rutland | Standard | 196 | $71,500 | 29.9 | 75.0% |
| 57050 | Nunda | Standard | 176 | $116,563 | 35.2 | -25.4% |