County Maps US

Clay County, South Dakota

A county in South Dakota, ranked 14 of 66 by population.

CountyFIPS 46027

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

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Population
15,031
+27 (+0.2%) since 2020
Land area
412
square miles. A further 1.3% of the total area is water
Population density
36.5
people per square mile, computed rather than published
County seat
Vermillion
Seat of county government.
Established
1862
163 years ago
Largest city
Vermillion city
Population 11,720.

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 Clay 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 Clay 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 575 by 800 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 Clay 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
Population15,03114th of 662,095th of 3,144
Land area412 sq mi66th of 662,455th of 3,144
Population density36.5 per sq mi10th of 661,760th of 3,144
Median household income$56,85057th of 662,342nd of 3,143

Full data for Clay County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population15,031Vintage 2025 Population Estimates
Population in 202015,004Vintage 2025 Population Estimates
2020 estimates base?14,973Vintage 2025 Population Estimates
Land area412 sq mi2025 Gazetteer Files
Water area5.4 sq mi2025 Gazetteer Files
Total area417.4 sq mi2025 Gazetteer Files
Population density?36.5 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$56,850American Community Survey 2020-2024 5-Year Estimates
Median home value$232,300American Community Survey 2020-2024 5-Year Estimates
Median age24.9American Community Survey 2020-2024 5-Year Estimates
Households5,547American Community Survey 2020-2024 5-Year Estimates
Housing units6,262American 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
-41
93 births, 134 deaths
Net migration
-119
More people moved out than moved in.

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

The 6 areas bordering Clay 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
Union CountySouth Dakota26 mi17,402
Yankton CountySouth Dakota20 mi23,635
Dixon CountyNebraska14 mi5,602
Turner CountySouth Dakota12 mi9,314
Cedar CountyNebraska8.6 mi8,373
Lincoln CountySouth Dakota6.0 mi77,145

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.