County Maps US

Grundy County, Illinois

A county in Illinois, ranked 25 of 102 by population.

CountyFIPS 17063

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

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Population
54,052
+1,514 (+2.9%) since 2020
Land area
418.1
square miles. A further 2.9% of the total area is water
Population density
129
people per square mile, computed rather than published
County seat
Morris
Seat of county government.
Established
1841
184 years ago
Largest city
Morris city
Population 14,669.

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 Grundy 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 Grundy County, Illinois 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 623 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 Grundy County ranks

Position among the 102 counties of Illinois, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn IllinoisNationally
Population54,05225th of 102963rd of 3,144
Land area418.1 sq mi69th of 1022,422nd of 3,144
Population density129 per sq mi22nd of 102762nd of 3,144
Median household income$92,23510th of 102263rd of 3,143

Full data for Grundy County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population54,052Vintage 2025 Population Estimates
Population in 202052,538Vintage 2025 Population Estimates
2020 estimates base?52,559Vintage 2025 Population Estimates
Land area418.1 sq mi2025 Gazetteer Files
Water area12.4 sq mi2025 Gazetteer Files
Total area430.5 sq mi2025 Gazetteer Files
Population density?129 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$92,235American Community Survey 2020-2024 5-Year Estimates
Median home value$271,700American Community Survey 2020-2024 5-Year Estimates
Median age38.3American Community Survey 2020-2024 5-Year Estimates
Households20,595American Community Survey 2020-2024 5-Year Estimates
Housing units21,384American 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
+17
501 births, 484 deaths
Net migration
+311
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 Grundy 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
LaSalle CountyIllinois24 mi107,773
Will CountyIllinois18 mi712,253
Kendall CountyIllinois18 mi145,470
Livingston CountyIllinois17 mi35,057
Kankakee CountyIllinois6.6 mi105,525

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

All 102 counties of Illinois

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

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