Grundy County, Illinois

County in IL, US

By Neilsberg Research

Last updated May 1, 2026

Key Indicators

A quick look at key numbers

Population

53,219

Source: U.S. Census Bureau American Community Survey (ACS) 2020-2024 5-Year Estimates

Median Age

38.3

years ∙ half population younger than 38.3, half older

Diversity Index

30.5%

chance two random people differ in race and ethnicity

Nativity

4.1%

foreign-born population

95.9%Native

4.1% Foreign-born

Geographic Context

Location, size, and surroundings

About

Grundy County is a county in Illinois, United States.

Location

County in IL, US

Co-ordinates

DEC41.292410° N, 88.401054° W

DMS41° 17′ 32.68″ N, 88° 24′ 03.79″ W

Population Density & area

127.3/sq mi (49.14/km²)

Total Area

430.5 sq mi (1,115 km²)

Land Area

418.1 sq mi (1,082.9 km²) · 97.1%

Water Area

12.4 sq mi (32.1 km²) · 2.9%

Demographics & Living

Who lives here, how households are formed, and community composition

Population Composition

Key characteristics of the population

Sex Distribution

50.4% male

Male 50.4%

Female 49.6%

males per 100 females

Grundy County 101.5

Illinois 97.7

United States 98

Nativity

4.1%

foreign-born population

95.9%Native

4.1% Foreign-born

% Foreign-born

Grundy County 4.1%

Illinois 14.7%

United States 14.1%

Age Distribution

How the population is spread across age groups

Median Age

38.3

years ∙ half population younger than 38.3, half older

Grundy County

38.3

Illinois

United States

38.9

Dependency ratio

dependents per 100 working-age adults

Grundy County 65

Illinois 63.5

United States 64.4

AGE DISTRIBUTION

Distribution of age group

Median age

	Grundy County	Illinois	United States
Age Group
Children (Under 18)	24.3%	21.8%	22%
Working age (18-64)	60.6%	61.2%	60.8%
Senior (65+)	15.1%	17%	17.2%
Dependency ratio
Total dependency ratio	65	63.5	64.4
Child dependency ratio	40.1	35.7	36.1
Old-age dependency ratio	24.9	27.8	28.3

Racial & Ethnic Composition

Racial and ethnic makeup and how it compares

Race & Ethnicity

White

82.4%

Black

2.3%

Asian

0.6%

Hispanic

12%

Other

2.7%

Note: White, Black, and Asian refer to individuals belonging to a single race and not of Hispanic origin. Hispanics may be of any race.

Diversity Index

30.5%

chance two random people differ in race and ethnicity

Grundy County 30.5%

Illinois 60.5%

United States 61.4%

Note: The Diversity Index (DI), based on the Blau Index, measures the probability that two randomly selected individuals differ in race and ethnicity. Values range from 0 (no diversity) to 1 (high diversity) and are shown as percentages.

RACIAL & ETHNIC COMPOSITION

Race & Ethnicity

Percentage of Grundy County population

	Grundy County	Illinois	United States
Hispanic or Latino	12%	18.8%	19.3%
Mexican	9.4%	14.4%	11.3%
Puerto Rican	1.8%	1.6%	1.8%
Cuban	0%	0.3%	0.8%
Other Hispanic / Latino	0.7%	2.5%	5.5%
Not Hispanic or Latino	88%	81.2%	80.7%
One race	85.6%	77.8%	76.4%
White	82.4%	58.1%	57.4%
Black or African American	2.3%	13.3%	11.9%
American Indian and Alaska Native	0.1%	0.1%	0.5%
Asian	0.6%	5.9%	5.9%
Native Hawaiian and Other Pacific Islander	0%	0%	0.2%
Some Other Race	0.3%	0.4%	0.6%
Two or more races (Multiracial)	2.4%	3.4%	4.3%

Household & Families Composition

Household size, type, and family structure

Household structure

67.9% family

Family 67.9%

Non family 32.1%

% family households

Grundy County 67.9%

Illinois 62.2%

United States 64.2%

Average household size

2.57

persons per household

Grundy County

2.57

Illinois

2.46

United States

2.53

Household & Family COMPOSITION

Households

Percentage of Grundy County population

	Grundy County	Illinois	United States
Total households	20,595	5,036,449	129,227,496
Average houshold size	2.57	2.46	2.53
Family households	13,983	3,130,978	82,990,528
Average family size	3.12	3.14	3.14
Married couple family	10,841	2,282,435	60,637,388
Other families	3,142	848,543	22,353,140
Male householder	1,167	248,521	6,572,819
Female householder	1,975	600,022	15,780,321
Non-family households	6,612	1,905,471	46,236,968
One-person households	5,174	1,569,881	37,140,836
Male householder	2,505	712,191	16,871,444
Senior (65+) living alone	702	210,051	5,225,110
Female householder	2,669	857,690	20,269,392
Senior (65+) living alone	1,503	417,870	10,089,070
Other living arrangements	1,438	335,590	9,096,132

Housing Profile

Housing stock, ownership, rentals, and cost burdens

Total housing units

21,384

housing units

Grundy County 21,384

Illinois 5,457,452

United States 143,775,355

Occupancy status

96.3% occupied

Occupied 96.3%

Vacant 3.7%

vacancy rate

Grundy County 3.7%

Illinois 7.7%

United States 10.1%

Housing Characteristics

How the housing supply is structured and used

Types of Housing unit

81.2%

Single family houses

81.2%

Apartments in multi-unit structures

14.8%

Mobile homes

3.9%

Boat, RV, van, etc

Median Year Built

1991

Half of houses were built before 1991, and half after.

Historic ∙ 1939 or earlier

11.2%

Postwar & mid-century ∙ 1940 - 1969

15.1%

Late 20th century ∙ 1970 - 1999

37.7%

Modern ∙ 2000 or later

36%

Note: Median year built reflects occupied units only; distribution includes all units.

Housing Characteristics

Units, rooms & bedrooms

Physical characteristics of housing units

	Grundy County	Illinois	United States
Rooms per unit
Median rooms	6.1	5.6	5.5
1–3 rooms	7.4%	14.6%	15.1%
4–6 rooms	49.6%	50.9%	51.6%
7+ rooms	42.9%	34.6%	33.4%
Bedrooms
No bedroom / studio	1.1%	3.1%	2.9%
1 bedroom	4.8%	11.5%	10.9%
2 bedrooms	24.4%	27.7%	25%
3 bedrooms	43.8%	35.8%	38.7%
4+ bedrooms	25.9%	21.7%	22.4%
At a glance
Median year built	1991	1971	1981
Total housing units	21,384	5,457,452	143,775,355

Occupancy Profile

Who is inside and how they use it

Homeownership

74.4% owners

Renter-occupied 25.6%

Owner-occupied 74.4%

homeownership rate

Grundy County 74.4%

Illinois 67.1%

United States 65.2%

Average household size

2.76

Owner-occupied

2.02

Renter-occupied

owner-occupied average size

Grundy County 2.76

Illinois 2.62

United States 2.64

Housing Characteristics

Occupied unit characteristics

Tenure, crowding, and utilities

	Grundy County	Illinois	United States
Total occupied units	20,595	5,036,449	129,227,496
Year moved in
2020 or later	23.9%	23.3%	24.8%
2010 to 2019	39.4%	38.1%	39.6%
2000 to 2009	19.2%	17.3%	16.4%
1999 or earlier	17.6%	21.3%	19.1%
Occupants per room
1.00 or fewer	97.6%	97.5%	96.6%
1.01 to 1.50	2%	1.6%	2.2%
1.51 or more	0.3%	0.8%	1.2%
Vehicles availability
No vehicles	4%	11%	8.4%
1 vehicle	27%	35.7%	33.1%
2 vehicles	41.6%	35.1%	36.6%
3 or more vehicles	27.5%	18.3%	21.9%
House heating fuel used
Gas	85%	79.5%	51.4%
Electricity	13.8%	18.6%	41.3%
Solar	0%	0.1%	0.3%
Fuel oil, kerosene etc	0%	0.1%	3.9%
All other fuels	1%	0.8%	2%
No fuel used	0.3%	0.8%	1.2%
Selected characteristics
Lacking complete plumbing	0.3%	0.3%	0.4%
Lacking complete kitchen	1.1%	0.8%	0.8%
No telephone service available	0.3%	0.8%	0.9%

Housing Value

What owner-occupied units are worth

Median home value

$271,700

owner-occupied units

Median value(USD)

Grundy County

$271,700

Illinois

$263,300

United States

$332,700

Housing Cost Burden

24.1%

of homeowners with a mortgage are cost-burdened

% Cost-Burdened Households

Owners with a mortgage

24.1%

Owners without a mortgage

12%

Renters

40.1%

Note: Households spending 30% or more of their income on housing costs are considered cost-burdened.

Financial characteristics

Property value and housing costs

Tenure, crowding, and utilities

	Grundy County	Illinois	United States
Property value
Median Value	$271,700	$263,300	$332,700
Under $100,000	7.3%	13.7%	11.4%
$100,000 - $200,000	18.6%	21.5%	15.8%
$200,000 - $300,000	31.9%	22.3%	17.8%
$300,000 - $500,000	36.3%	27.7%	26.9%
$500,000 - $1,000,000	4.7%	12.1%	20.9%
$1,000,000 and more	1.2%	2.7%	7.1%
Owner-occupied households
With a mortgage	66.7%	60.8%	60.6%
Without a mortgage	33.3%	39.2%	39.4%
Median monthly owner costs
With a mortgage	$2,016	$1,987	$1,963
Without a mortgage	$800	$792	$638
Gross rent
Median rent	$1,177	$1,274	$1,413

Education Profile

How educated is the community and how education pays off

Adults with a college degree

23.6%

of adults 25+ with a bachelor's degree or higher

Grundy County 23.6%

Illinois 37.8%

United States 35.7%

Adults without a high school diploma

6.2%

of adults (25+) without a high school diploma

Grundy County 6.2%

Illinois 9.6%

United States 10.4%

School Enrollment

Who is enrolled in school and at what level

School enrollment

12,865

population (age 3+) enrolled in school

Nursery / Preschool

8.7%

K–12

71.4%

College / Undergraduate

17.1%

Graduate / Professional

2.8%

College-going rate (18-24 yr olds)

35.6%

of 18-24-year-olds in college or graduate school

Grundy County

35.6%

Illinois

41.4%

United States

40.9%

Enrollment & school type

Enrollment levels, college-going rate, and public vs private school split

Population 3+ currently enrolled in a school

	Grundy County	Illinois	United States
Total enrolled (age 3+)	12,865	3,051,569	80,089,790
Nursery / preschool	8.7%	6.3%	5.7%
K–12	71.4%	67.3%	67.6%
Kindergarten	5.1%	4.9%	5%
Elementary: Grades 1–4	22.2%	19.5%	19.8%
Elementary: Grades 5–8	19.2%	20.8%	21%
High School: Grades 9–12	24.9%	22.1%	21.7%
College or graduate school	19.9%	26.4%	26.7%
College, undergraduate	17.1%	19.8%	21%
Graduate, professional school	2.8%	6.6%	5.8%
College-going rate · 18-24 yr olds	35.6%	41.4%	40.9%
School type
Public school	89.2%	80.5%	82%
Private school	10.8%	19.5%	18%

Education Attainment by Level & Gender

What is the highest level of education completed among adults

Education attainment

35,595

population 25 years and over

Total adults (25+)

Less than 9th grade

2.1%

9th-12th, no diploma

4.1%

HS graduate

33.9%

Some college no degree

25.5%

Associates degree

10.8%

Bachelors degree

16.1%

Graduate or professional degree

7.5%

Attainment by gender

Male vs Female

Adults (25+) · Share within each education level

% male · % female

Less than 9th grade

57% · 43%

9th-12th, no diploma

47.2% · 52.8%

HS graduate

53.8% · 46.2%

Some college no degree

47.4% · 52.6%

Associates degree

47.4% · 52.6%

Bachelors degree

46.5% · 53.5%

Graduate or professional degree

46.9% · 53.1%

Educational Attainment Overview

Distribution and key education attainment rates for adults (25+)

Highest credential completed · adults 25+

	Grundy County	Illinois	United States
Population (25+)	35,595	8,767,004	230,807,303
Less than 9th grade	2.1%	4.6%	4.7%
9th–12th, no diploma	4.1%	5%	5.7%
High school diploma or GED	33.9%	25.1%	26%
Some college, no degree	25.5%	19.2%	19.1%
Associate's degree	10.8%	8.3%	8.8%
Bachelor's degree or higher	23.6%	37.8%	35.7%
Bachelor's degree	16.1%	22.6%	21.6%
Graduate or professional	7.5%	15.3%	14.1%
High School or higher	93.8%	90.5%	89.6%

Earnings by education level

percentage as applicable

Median Earnings

$57,775

Median earnings for adults 25+, by level

Less than HS graduate

$36,635

HS graduate

$47,073

Some college or associates

$52,370

Bachelors degree

$81,630

Graduate or professional degree

$84,537

Poverty Rate

1.5%

for ages 25+, with bachelors degree or higher

Less than HS graduate

14.6%

HS graduate

7.1%

Some college or associates

4.4%

Bachelors degree or higher

1.5%

Outcomes by Education Level

Earnings and poverty rates across education levels (25+)

Adults 25+

	Grundy County	Illinois	United States
Median earnings
Population 25+, with earnings	$57,775	$55,582	$52,696
Less than high school graduate	$36,635	$34,655	$32,485
High school graduate (includes equivalency)	$47,073	$40,965	$40,153
Some college or associate's degree	$52,370	$47,813	$47,260
Bachelor's degree	$81,630	$73,326	$70,044
Graduate or professional degree	$84,537	$91,623	$90,720
Poverty rates
Less than high school graduate	14.6%	21.6%	24.2%
High school graduate (includes equivalency)	7.1%	14.4%	14.4%
Some college or associate's degree	4.4%	9.9%	9.8%
Bachelor's degree or higher	1.5%	4.5%	4.5%

Insights for Grundy County, by topic

Income By year By race By age By gender

Population By year By race By age By gender

About Neilsberg Research

Neilsberg Research team are data scientists with expertise in processing, analysis and visualization of big data helping small businesses make right decisions.

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