ZIP Codes of Buffalo County, SD

Population & People
Population & People
Total Population
1,469
Household Income
Household Income
Median Income
$46,136
Housing
Housing
Total Housing Units
454
Business & Economy
Business & Economy
Total Businesses
9
Employment
Employment
Employment Rate
47.36%
Education
Education
Bachelor's Degree+
10.18%
Source: U.S. Census ACS 2024 5-Year Estimates · rolled up across the 2 ZIPs in this county.
Data Last Updated: June 1, 2026
ZIP Codes:2 ZIP Codes (2 Standard, 0 PO Box, 0 Unique) [See All]
Area Code:605
Timezone:Central (GMT -06:00)
Local Time:2:13:41 PM
Population:1,469 [See All]
FIPS:46017
Land Area:324 sq mi
Water Area:11 sq mi
Coordinates:44.0807, -99.2999
Quick Link:
https://www.zip-codes.com/county/sd-buffalo.asp
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Notable population decline
Lost 14.2% of residents since 2014.
Among America's 25 youngest counties
Median age 22.0 — #12 youngest nationwide.
Among South Dakota's 5 most renter-heavy counties
53.9% of homes rented — #2 statewide.

Standout ZIPs in this County


Most Populous
Fort Thompson · 1,390 people
94.6% of county total
Highest Income
Fort Thompson · $46,136 median
1.0× county average
Largest Land Area
Gann Valley · 256.5 sq mi
Spans the most ground
Fastest Growth
Fort Thompson · -10.7% (10-yr)
1,556 → 1,390 residents
Most Educated
— no education data

Things worth knowing about Buffalo County


1,469 residents live across 2 ZIPs covering 324 sq mi, served by 2 distinct USPS-recognized cities.

Population moved from 1,713 to 1,469 from 2014 to 2024 — a -14.2% change. 0 ZIPs gained residents, 2 lost.

The county's wealthiest ZIP 57339 (Fort Thompson, $46,136 median) and poorest ZIP 57339 (Fort Thompson, $46,136) are 0.0 miles apart — a 1.0× income gap across local geography.

Density varies 67× across the county — from 0 people/sq mi in 57341 (Gann Valley) to 21 in 57339 (Fort Thompson).

Within South Dakota, this is the #65 most populous of 82 counties and ranks #80 for median household income .

Weighted by population, the typical household earns about $46,136 across the county — reflecting what a typical resident sees, not a simple ZIP average.

10.2% of adults age 25+ hold a bachelor's degree or higher (68 of 668 reporting).

2 Standard delivery, 0 PO Box only, 0 single-entity Unique ZIPs serve this county.

Stories about Buffalo County


Single-ZIP anchor

One ZIP holds the majority of this county's population — a sign of a county built around a single city or town.

Fort Thompson

Population decline

Buffalo County lost 14.2% of residents between 2014 and 2024. ZIPs that shed the largest share:

Fort Thompson
-10.7%
1,556 → 1,390 residents

All ZIP Codes in Buffalo County


ZIPCityTypePopulationMedian IncomeArea (sq mi)10-yr Growth
57339Fort ThompsonStandard1,390$46,13667.0-10.7%
57341Gann ValleyStandard79256.5-49.7%

Adjacent & Nearby Counties