County Maps US

Lyon County, Iowa

A county in Iowa, ranked 61 of 99 by population.

CountyFIPS 19119

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

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Population
12,354
+430 (+3.6%) since 2020
Land area
587.6
square miles. A further 0.0% of the total area is water
Population density
21.0
people per square mile, computed rather than published
County seat
Rock Rapids
Seat of county government.
Established
1851
174 years ago
Largest city
Rock Rapids city
Population 2,733.

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 Lyon 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 Lyon 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 408 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 Lyon 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
Population12,35461st of 992,265th of 3,144
Land area587.6 sq mi25th of 991,667th of 3,144
Population density21.0 per sq mi69th of 992,206th of 3,144
Median household income$76,74624th of 99738th of 3,143

Full data for Lyon County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population12,354Vintage 2025 Population Estimates
Population in 202011,924Vintage 2025 Population Estimates
2020 estimates base?11,932Vintage 2025 Population Estimates
Land area587.6 sq mi2025 Gazetteer Files
Water area0.17 sq mi2025 Gazetteer Files
Total area587.8 sq mi2025 Gazetteer Files
Population density?21.0 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$76,746American Community Survey 2020-2024 5-Year Estimates
Median home value$230,000American Community Survey 2020-2024 5-Year Estimates
Median age38.2American Community Survey 2020-2024 5-Year Estimates
Households4,479American Community Survey 2020-2024 5-Year Estimates
Housing units4,870American 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
133 births, 130 deaths
Net migration
-53
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 7 areas bordering Lyon 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
Sioux CountyIowa35 mi36,774
Lincoln CountySouth Dakota32 mi77,145
Rock CountyMinnesota20 mi9,524
Osceola CountyIowa17 mi5,980
Nobles CountyMinnesota9.7 mi22,338
Minnehaha CountySouth Dakota7.3 mi212,691
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.