County Maps US

Plymouth County, Iowa

A county in Iowa, ranked 25 of 99 by population.

CountyFIPS 19149

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

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Population
25,697
0 (0%) since 2020
Land area
862.8
square miles. A further 0.1% of the total area is water
Population density
29.8
people per square mile, computed rather than published
County seat
Le Mars
Seat of county government.
Established
1851
174 years ago
Largest city
Le Mars city
Population 10,760.

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 Plymouth 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 Plymouth County, Iowa 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 521 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 Plymouth County ranks

Position among the 99 counties of Iowa, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn IowaNationally
Population25,69725th of 991,599th of 3,144
Land area862.8 sq mi4th of 99958th of 3,144
Population density29.8 per sq mi41st of 991,929th of 3,144
Median household income$83,25111th of 99477th of 3,143

Full data for Plymouth County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population25,697Vintage 2025 Population Estimates
Population in 202025,697Vintage 2025 Population Estimates
2020 estimates base?25,703Vintage 2025 Population Estimates
Land area862.8 sq mi2025 Gazetteer Files
Water area0.84 sq mi2025 Gazetteer Files
Total area863.7 sq mi2025 Gazetteer Files
Population density?29.8 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$83,251American Community Survey 2020-2024 5-Year Estimates
Median home value$228,900American Community Survey 2020-2024 5-Year Estimates
Median age41.3American Community Survey 2020-2024 5-Year Estimates
Households10,313American Community Survey 2020-2024 5-Year Estimates
Housing units10,891American 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
-3
287 births, 290 deaths
Net migration
+17
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 Plymouth 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 Dakota55 mi17,402
Sioux CountyIowa34 mi36,774
Woodbury CountyIowa33 mi106,649
Cherokee CountyIowa24 mi11,369
O'Brien CountyIowaa single point14,220

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

All 99 counties of Iowa

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

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