Marion County, Illinois

County in IL, US

By Neilsberg Research

Last updated May 1, 2026

Key Indicators

A quick look at key numbers

Population

37,000

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

Median Age

41.5

years ∙ half population younger than 41.5, half older

Diversity Index

20.3%

chance two random people differ in race and ethnicity

Nativity

1.5%

foreign-born population

98.5%Native

1.5% Foreign-born

Geographic Context

Location, size, and surroundings

About

Marion County is a county in Illinois, United States.

Location

County in IL, US

Co-ordinates

DEC38.648236° N, 88.920362° W

DMS38° 38′ 53.65″ N, 88° 55′ 13.30″ W

Population Density & area

64.63/sq mi (24.95/km²)

Total Area

576.1 sq mi (1,492.1 km²)

Land Area

572.5 sq mi (1,482.9 km²) · 99.38%

Water Area

3.6 sq mi (9.2 km²) · 0.62%

Demographics & Living

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

Population Composition

Key characteristics of the population

Sex Distribution

49.2% male

Male 49.2%

Female 50.8%

males per 100 females

Marion County 96.9

Illinois 97.7

United States 98

Nativity

1.5%

foreign-born population

98.5%Native

1.5% Foreign-born

% Foreign-born

Marion County 1.5%

Illinois 14.7%

United States 14.1%

Age Distribution

How the population is spread across age groups

Median Age

41.5

years ∙ half population younger than 41.5, half older

Marion County

41.5

Illinois

United States

38.9

Dependency ratio

77.5

dependents per 100 working-age adults

Marion County 77.5

Illinois 63.5

United States 64.4

AGE DISTRIBUTION

Distribution of age group

Median age

	Marion County	Illinois	United States
Age Group
Children (Under 18)	23.5%	21.8%	22%
Working age (18-64)	56.3%	61.2%	60.8%
Senior (65+)	20.2%	17%	17.2%
Dependency ratio
Total dependency ratio	77.5	63.5	64.4
Child dependency ratio	41.7	35.7	36.1
Old-age dependency ratio	35.9	27.8	28.3

Racial & Ethnic Composition

Racial and ethnic makeup and how it compares

Race & Ethnicity

White

89.1%

Black

2.9%

Asian

0.7%

Hispanic

2.2%

Other

5.1%

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

20.3%

chance two random people differ in race and ethnicity

Marion County 20.3%

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 Marion County population

	Marion County	Illinois	United States
Hispanic or Latino	2.2%	18.8%	19.3%
Mexican	1.3%	14.4%	11.3%
Puerto Rican	0.3%	1.6%	1.8%
Cuban	0%	0.3%	0.8%
Other Hispanic / Latino	0.5%	2.5%	5.5%
Not Hispanic or Latino	97.8%	81.2%	80.7%
One race	93.6%	77.8%	76.4%
White	89.1%	58.1%	57.4%
Black or African American	2.9%	13.3%	11.9%
American Indian and Alaska Native	0.1%	0.1%	0.5%
Asian	0.7%	5.9%	5.9%
Native Hawaiian and Other Pacific Islander	0%	0%	0.2%
Some Other Race	0.8%	0.4%	0.6%
Two or more races (Multiracial)	4.2%	3.4%	4.3%

Household & Families Composition

Household size, type, and family structure

Household structure

61% family

Family 61%

Non family 39%

% family households

Marion County 61%

Illinois 62.2%

United States 64.2%

Average household size

2.33

persons per household

Marion County

2.33

Illinois

2.46

United States

2.53

Household & Family COMPOSITION

Households

Percentage of Marion County population

	Marion County	Illinois	United States
Total households	15,512	5,036,449	129,227,496
Average houshold size	2.33	2.46	2.53
Family households	9,462	3,130,978	82,990,528
Average family size	2.99	3.14	3.14
Married couple family	6,833	2,282,435	60,637,388
Other families	2,629	848,543	22,353,140
Male householder	928	248,521	6,572,819
Female householder	1,701	600,022	15,780,321
Non-family households	6,050	1,905,471	46,236,968
One-person households	5,402	1,569,881	37,140,836
Male householder	2,769	712,191	16,871,444
Senior (65+) living alone	1,130	210,051	5,225,110
Female householder	2,633	857,690	20,269,392
Senior (65+) living alone	1,433	417,870	10,089,070
Other living arrangements	648	335,590	9,096,132

Housing Profile

Housing stock, ownership, rentals, and cost burdens

Total housing units

17,334

housing units

Marion County 17,334

Illinois 5,457,452

United States 143,775,355

Occupancy status

89.5% occupied

Occupied 89.5%

Vacant 10.5%

vacancy rate

Marion County 10.5%

Illinois 7.7%

United States 10.1%

Housing Characteristics

How the housing supply is structured and used

Types of Housing unit

72.2%

Single family houses

72.2%

Apartments in multi-unit structures

10.6%

Mobile homes

16.9%

Boat, RV, van, etc

0.2%

Median Year Built

1974

Half of houses were built before 1974, and half after.

Historic ∙ 1939 or earlier

14.8%

Postwar & mid-century ∙ 1940 - 1969

30.1%

Late 20th century ∙ 1970 - 1999

40.3%

Modern ∙ 2000 or later

14.9%

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

Housing Characteristics

Units, rooms & bedrooms

Physical characteristics of housing units

	Marion County	Illinois	United States
Rooms per unit
Median rooms	5.7	5.6	5.5
1–3 rooms	9.4%	14.6%	15.1%
4–6 rooms	57.6%	50.9%	51.6%
7+ rooms	33.1%	34.6%	33.4%
Bedrooms
No bedroom / studio	2.6%	3.1%	2.9%
1 bedroom	7.9%	11.5%	10.9%
2 bedrooms	28.7%	27.7%	25%
3 bedrooms	43.7%	35.8%	38.7%
4+ bedrooms	17.2%	21.7%	22.4%
At a glance
Median year built	1974	1971	1981
Total housing units	17,334	5,457,452	143,775,355

Occupancy Profile

Who is inside and how they use it

Homeownership

74.7% owners

Renter-occupied 25.3%

Owner-occupied 74.7%

homeownership rate

Marion County 74.7%

Illinois 67.1%

United States 65.2%

Average household size

2.4

Owner-occupied

2.12

Renter-occupied

owner-occupied average size

Marion County 2.4

Illinois 2.62

United States 2.64

Housing Characteristics

Occupied unit characteristics

Tenure, crowding, and utilities

	Marion County	Illinois	United States
Total occupied units	15,512	5,036,449	129,227,496
Year moved in
2020 or later	19.7%	23.3%	24.8%
2010 to 2019	37.9%	38.1%	39.6%
2000 to 2009	17.8%	17.3%	16.4%
1999 or earlier	24.6%	21.3%	19.1%
Occupants per room
1.00 or fewer	98.8%	97.5%	96.6%
1.01 to 1.50	0.6%	1.6%	2.2%
1.51 or more	0.5%	0.8%	1.2%
Vehicles availability
No vehicles	7%	11%	8.4%
1 vehicle	33.4%	35.7%	33.1%
2 vehicles	38.1%	35.1%	36.6%
3 or more vehicles	21.5%	18.3%	21.9%
House heating fuel used
Gas	69.1%	79.5%	51.4%
Electricity	28%	18.6%	41.3%
Solar	0%	0.1%	0.3%
Fuel oil, kerosene etc	0%	0.1%	3.9%
All other fuels	2.3%	0.8%	2%
No fuel used	0.6%	0.8%	1.2%
Selected characteristics
Lacking complete plumbing	0.6%	0.3%	0.4%
Lacking complete kitchen	1.6%	0.8%	0.8%
No telephone service available	1.4%	0.8%	0.9%

Housing Value

What owner-occupied units are worth

Median home value

$103,000

owner-occupied units

Median value(USD)

Marion County

$103,000

Illinois

$263,300

United States

$332,700

Housing Cost Burden

21%

of homeowners with a mortgage are cost-burdened

% Cost-Burdened Households

Owners with a mortgage

21%

Owners without a mortgage

13.3%

Renters

42.6%

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

	Marion County	Illinois	United States
Property value
Median Value	$103,000	$263,300	$332,700
Under $100,000	48.6%	13.7%	11.4%
$100,000 - $200,000	31.1%	21.5%	15.8%
$200,000 - $300,000	11.5%	22.3%	17.8%
$300,000 - $500,000	6.4%	27.7%	26.9%
$500,000 - $1,000,000	2%	12.1%	20.9%
$1,000,000 and more	0.4%	2.7%	7.1%
Owner-occupied households
With a mortgage	50.9%	60.8%	60.6%
Without a mortgage	49.1%	39.2%	39.4%
Median monthly owner costs
With a mortgage	$1,206	$1,987	$1,963
Without a mortgage	$522	$792	$638
Gross rent
Median rent	$794	$1,274	$1,413

Education Profile

How educated is the community and how education pays off

Adults with a college degree

16.8%

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

Marion County 16.8%

Illinois 37.8%

United States 35.7%

Adults without a high school diploma

9.3%

of adults (25+) without a high school diploma

Marion County 9.3%

Illinois 9.6%

United States 10.4%

School Enrollment

Who is enrolled in school and at what level

School enrollment

8,287

population (age 3+) enrolled in school

Nursery / Preschool

9.8%

K–12

73.9%

College / Undergraduate

14.1%

Graduate / Professional

2.3%

College-going rate (18-24 yr olds)

30.5%

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

Marion County

30.5%

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

	Marion County	Illinois	United States
Total enrolled (age 3+)	8,287	3,051,569	80,089,790
Nursery / preschool	9.8%	6.3%	5.7%
K–12	73.9%	67.3%	67.6%
Kindergarten	6.3%	4.9%	5%
Elementary: Grades 1–4	20.3%	19.5%	19.8%
Elementary: Grades 5–8	25.5%	20.8%	21%
High School: Grades 9–12	21.8%	22.1%	21.7%
College or graduate school	16.4%	26.4%	26.7%
College, undergraduate	14.1%	19.8%	21%
Graduate, professional school	2.3%	6.6%	5.8%
College-going rate · 18-24 yr olds	30.5%	41.4%	40.9%
School type
Public school	85.5%	80.5%	82%
Private school	14.5%	19.5%	18%

Education Attainment by Level & Gender

What is the highest level of education completed among adults

Education attainment

25,698

population 25 years and over

Total adults (25+)

Less than 9th grade

2.3%

9th-12th, no diploma

HS graduate

36.8%

Some college no degree

24.7%

Associates degree

12.5%

Bachelors degree

11.5%

Graduate or professional degree

5.3%

Attainment by gender

Male vs Female

Adults (25+) · Share within each education level

% male · % female

Less than 9th grade

61.9% · 38.1%

9th-12th, no diploma

53% · 47%

HS graduate

53.2% · 46.8%

Some college no degree

46.4% · 53.6%

Associates degree

36.4% · 63.6%

Bachelors degree

44.8% · 55.2%

Graduate or professional degree

50.5% · 49.5%

Educational Attainment Overview

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

Highest credential completed · adults 25+

	Marion County	Illinois	United States
Population (25+)	25,698	8,767,004	230,807,303
Less than 9th grade	2.3%	4.6%	4.7%
9th–12th, no diploma	7%	5%	5.7%
High school diploma or GED	36.8%	25.1%	26%
Some college, no degree	24.7%	19.2%	19.1%
Associate's degree	12.5%	8.3%	8.8%
Bachelor's degree or higher	16.8%	37.8%	35.7%
Bachelor's degree	11.5%	22.6%	21.6%
Graduate or professional	5.3%	15.3%	14.1%
High School or higher	90.7%	90.5%	89.6%

Earnings by education level

percentage as applicable

Median Earnings

$44,911

Median earnings for adults 25+, by level

Less than HS graduate

$32,639

HS graduate

$37,282

Some college or associates

$45,776

Bachelors degree

$55,164

Graduate or professional degree

$70,313

Poverty Rate

4.2%

for ages 25+, with bachelors degree or higher

Less than HS graduate

31.1%

HS graduate

18.1%

Some college or associates

9.5%

Bachelors degree or higher

4.2%

Outcomes by Education Level

Earnings and poverty rates across education levels (25+)

Adults 25+

	Marion County	Illinois	United States
Median earnings
Population 25+, with earnings	$44,911	$55,582	$52,696
Less than high school graduate	$32,639	$34,655	$32,485
High school graduate (includes equivalency)	$37,282	$40,965	$40,153
Some college or associate's degree	$45,776	$47,813	$47,260
Bachelor's degree	$55,164	$73,326	$70,044
Graduate or professional degree	$70,313	$91,623	$90,720
Poverty rates
Less than high school graduate	31.1%	21.6%	24.2%
High school graduate (includes equivalency)	18.1%	14.4%	14.4%
Some college or associate's degree	9.5%	9.9%	9.8%
Bachelor's degree or higher	4.2%	4.5%	4.5%

Insights for Marion 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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