County Maps US

Sully County, South Dakota

A county in South Dakota, ranked 62 of 66 by population.

CountyFIPS 46119

Within South Dakota
Sully County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data. The dot marks Onida, the county seat, located via the 2025 Census Gazetteer.

Download SVGFull South Dakota map downloads

Population
1,479
+28 (+1.9%) since 2020
Land area
1,007
square miles. A further 5.9% of the total area is water
Population density
1.5
people per square mile, computed rather than published
County seat
Onida
Seat of county government.
Established
1909
116 years ago
Largest city
Onida city
Population 640.

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.

Satellite view

Aerial imagery of Sully County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.

Aerial view of Sully County, South Dakota from the USGS National Map, with its boundary outlined
Imagery: USGS National Map, USGS Imagery Only, public domain, requested from USGS by your browser when you reach this point on the page, at 800 by 420 pixels. The boundary is the 2025 Census cartographic boundary file, reprojected to Web Mercator to match the imagery. You can also open the USGS National Map viewer.

Where Sully County ranks

Position among the 66 counties of South Dakota, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn South DakotaNationally
Population1,47962nd of 663,079th of 3,144
Land area1,007 sq mi30th of 66673rd of 3,144
Population density1.5 per sq mi59th of 663,030th of 3,144
Median household income$72,57834th of 661,009th of 3,143

Full data for Sully County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population1,479Vintage 2025 Population Estimates
Population in 20201,451Vintage 2025 Population Estimates
2020 estimates base?1,447Vintage 2025 Population Estimates
Land area1,007 sq mi2025 Gazetteer Files
Water area63.5 sq mi2025 Gazetteer Files
Total area1,070 sq mi2025 Gazetteer Files
Population density?1.5 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$72,578American Community Survey 2020-2024 5-Year Estimates
Median home value$205,400American Community Survey 2020-2024 5-Year Estimates
Median age46.9American Community Survey 2020-2024 5-Year Estimates
Households637American Community Survey 2020-2024 5-Year Estimates
Housing units934American Community Survey 2020-2024 5-Year Estimates

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.

How the population changed

The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:

Births minus deaths
-1
10 births, 11 deaths
Net migration
+8
More people moved in than moved out.

Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.

The 5 areas bordering Sully County

Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.

Bordering areaStateShared borderPopulation
Hughes CountySouth Dakota42 mi17,570
Potter CountySouth Dakota36 mi2,377
Dewey CountySouth Dakota27 mi5,419
Hyde CountySouth Dakota24 mi1,191
Stanley CountySouth Dakota23 mi3,018

Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.

All 66 counties of South Dakota

Open the interactive South Dakota county map, or jump straight to any of them.

Data on this page last rebuilt 30 August 2026. How these figures are produced.