Grundy County area

Population and density of Grundy County

The Census Bureau estimates that 54,052 people lived in Grundy County on July 1, 2025. That ranks #974 of 3,222 county equivalents nationally and #25 of 102 in Illinois. Since the April 1, 2020 estimates base of 52,559, the population has grown by 1,493 (+2.8%), compared with −0.8% for Illinois as a whole.

With 418.1 square miles of land, that is 129 people per square mile (50 per km²), placing Grundy County #839 nationally for density and #22 in Illinois. The median county equivalent has 47 people per square mile; the Illinois median is 44. Put another way, there are about 5 acres of land per resident.

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Grundy County

17 incorporated places lie at least partly in Grundy County. Together they are home to 42,167 people (78%); the other 11,885 (22%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Morris city, with 14,669 residents in the county. By land, Channahon village is the largest at 16.9 mi² across all its counties. Among places with at least 1,000 residents in 2020, Channahon village grew fastest since then (+9.8%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Grundy County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Grundy County is an outlying county of the Chicago-Naperville-Elgin, IL-IN Metropolitan Statistical Area, in the Chicago-Naperville-Schaumburg, IL metropolitan division. Its 13 county equivalents have 9,434,123 residents on 6,923.3 square miles of land; Grundy County accounts for 6% of the land and 0.6% of the residents. By combined land it ranks #27 of 393 metropolitan areas, and #3 by population. It belongs to the Chicago-Naperville, IL-IN-WI Combined Statistical Area.

ZIP codes

16 ZIP Code Tabulation Areas have land in Grundy County; 8 of them have most of their land inside the county, and the others mainly cover neighboring areas.

60407604106041660420604246043760444604476045060470604746047960481605416096161360

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Grundy County

Grundy County shares a land border with 5 county equivalents. It has more land than 1 of them. The largest neighbor is LaSalle County (1,135.1 mi²) and the smallest is Kendall County (320.2 mi²). Together with its neighbors, Grundy County forms a block of 4,429.5 mi² of land, of which it holds 9.4%.

How big is Grundy County compared with U.S. states?

Grundy County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.5 times as much. Illinois’s county land could hold about 133 areas the size of Grundy County.

Another way to picture it: the same land area would fill a square about 20.4 miles (32.9 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Grundy County?

Grundy County has more land than 800 of the other 3,221 county equivalents in the dataset.

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Grundy County at #2,444 nationally by total area, 22 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 2.9%, compared with a national county-equivalent median of 1.2% — 1.7 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Grundy County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.