County Maps US

Marshall County, South Dakota

A county in South Dakota, ranked 37 of 66 by population.

CountyFIPS 46091

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

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Population
4,426
+125 (+2.9%) since 2020
Land area
838.1
square miles. A further 5.4% of the total area is water
Population density
5.3
people per square mile, computed rather than published
County seat
Britton
Seat of county government.
Established
1885
140 years ago
Largest city
Britton city
Population 1,199.

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 Marshall 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 Marshall 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 600 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 Marshall 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
Population4,42637th of 662,858th of 3,144
Land area838.1 sq mi36th of 66998th of 3,144
Population density5.3 per sq mi35th of 662,757th of 3,144
Median household income$78,15615th of 66663rd of 3,143

Full data for Marshall County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population4,426Vintage 2025 Population Estimates
Population in 20204,301Vintage 2025 Population Estimates
2020 estimates base?4,304Vintage 2025 Population Estimates
Land area838.1 sq mi2025 Gazetteer Files
Water area48.1 sq mi2025 Gazetteer Files
Total area886.2 sq mi2025 Gazetteer Files
Population density?5.3 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$78,156American Community Survey 2020-2024 5-Year Estimates
Median home value$156,500American Community Survey 2020-2024 5-Year Estimates
Median age42.5American Community Survey 2020-2024 5-Year Estimates
Households1,651American Community Survey 2020-2024 5-Year Estimates
Housing units2,436American 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
+6
53 births, 47 deaths
Net migration
-14
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 5 areas bordering Marshall 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
Day CountySouth Dakota38 mi5,484
Sargent CountyNorth Dakota36 mi3,711
Roberts CountySouth Dakota26 mi10,255
Brown CountySouth Dakota24 mi37,561
Richland CountyNorth Dakotaa single point16,731

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.