DeKalb County, Illinois Population 2026

Updated April 2026 · US Census ACS 2023 5-Year Estimates · 20th-largest in Illinois

The population of DeKalb County, Illinois is 100,512 as of the 2023 American Community Survey, making it the 20th-largest county in Illinois. The median household income is $69,022, the median home value is $231,900, and the median age is 32.6.

The population of DeKalb County has declined 3.6% since 2010 (105,151 → 101,335), a -0.26% annualized rate.

DeKalb County within Illinois · Source: US Census TIGER/Line via us-atlas

100,512

Population

-0.26%

Annual growth

159

People / sq mi

$69,022

Median Income

$231,900

Median Home Value

DeKalb County covers 631 sq mi of land at 159.2 people per square mile.

About DeKalb County, IL

Age is the most distinctive thing about DeKalb County: a median age of 32.6, younger than the national median. With 100,512 residents, DeKalb County is a county in Illinois. It ranks #20 among counties in Illinois by population.

Median household income is $69,022, below the US median of $78,538. About 10.9% of residents live below the federal poverty level, below the national 12.4%. A typical home is worth $231,900, with typical rent around $1,041.

College attainment is above the local norm at 32.7%, below the national 35.0%. Around 7.6% of workers work from home, below the national 14.0%, and the average commute runs about 27 minutes each way.

DeKalb County Population History (2010-2024)

The county of DeKalb County had a population of 105,151 in 2010 and 101,335 in 2024, a -3.6% growth over 14 years. The peak was 105,151 in 2010. Average annual growth rate: -0.26%.

DeKalb County population, 2010–2024 · Source: U.S. Census Bureau — decennial census & Population Estimates

101,335

Population (2024)

105,151

Population (2010)

105,151

Peak (2010)

-0.26%

Avg Annual Growth

Year	Population	Change	Annual %	Source
2010	105,151	-	-	estimate
2011	104,466	-685	-0.65%	estimate
2012	104,385	-81	-0.08%	estimate
2013	104,226	-159	-0.15%	estimate
2014	104,593	+367	+0.35%	estimate
2015	104,238	-355	-0.34%	estimate
2016	104,219	-19	-0.02%	estimate
2017	104,513	+294	+0.28%	estimate
2018	104,587	+74	+0.07%	estimate
2019	105,131	+544	+0.52%	estimate
2020	100,368	-4,763	-4.53%	estimate
2021	100,584	+216	+0.22%	estimate
2022	100,569	-15	-0.01%	estimate
2023	100,661	+92	+0.09%	estimate
2024	101,335	+674	+0.67%	estimate

Race & Ethnicity

White	76.3%
Black or African American	7.8%
Asian	0.0%
Hispanic or Latino (any race)	1.4%
Two or More Races	0.0%

Age & Sex

32.6

Median Age

50.2%

Female

49.8%

Male

13.7%

Age 65+

Age Distribution

Under 5

5.5%

5–9

6.3%

10–14

6.1%

15–19

8.8%

20–24

13.2%

25–34

13.2%

35–44

11.9%

45–54

10.5%

55–59

5.9%

60–64

5.0%

65–74

8.2%

75–84

3.8%

85+

1.7%

Children (under 15): 17.9% · Seniors (65+): 13.7%

Income & Poverty

Median household income	$69,022$-12,680 vs state
Mean household income	$87,946
Per-capita income	$35,054
Poverty rate	10.9%+2.7% vs state
Unemployment rate	4.9%
Employment-to-population	64.1%

Top Industries by Employment

Professional & business services

27.2%

Manufacturing

11.6%

Education & health care

10.8%

Finance & real estate

9.0%

Retail trade

6.6%

Construction

6.2%

Information

4.5%

Arts, entertainment & food

3.9%

The largest employment sector in DeKalb County is professional & business services, accounting for 27.2% of workers.

How residents commute

0.9%

Drive alone

3.5%

Carpool

76.4%

Public transit

7.6%

Work from home

26.7 min

Avg commute

Housing

$231,900$-18,600 vs state

Median home value

$1,041

Median rent

60.9%

Homeownership rate

41,499

Total housing units

94.7%

Occupied

5.3%

Vacant

39.1%

Renter-occupied

Social & access

95.2%

With health insurance

96.1%

With broadband internet

15.1%

Foreign-born

5.1%

Veterans (18+)

11.0%

With a disability

88.0%

Speak language other than English at home

Education

92.4%

High School+

32.7%

Bachelor's+

Largest cities in Illinois

Chicago (2,707,648)Aurora (179,867)Joliet (149,785)Naperville (149,424)Rockford (147,649)Elgin (114,106)Springfield (113,714)Peoria (112,126)Waukegan (88,919)Champaign (88,822)All Illinois cities →

Other counties in Illinois

Cook County (5,185,812)DuPage County (927,263)Lake County (711,885)Will County (698,450)Kane County (516,097)McHenry County (311,366)Winnebago County (283,289)Madison County (264,631)St. Clair County (254,777)Champaign County (206,098)All Illinois counties →

Part of Illinois

Illinois demographic profile All Illinois data →

Metro areas in Illinois

Chicago (9,359,555)St. Louis (2,809,414)Davenport (381,864)Peoria (365,773)Rockford (336,605)Champaign (236,196)Springfield (207,386)Bloomington (170,882)All US metros →

County rankings

US Counties by Population Richest US Counties by Median Household Income Expensive US Counties by Home Value Educated US Counties Counties With Highest Poverty Rates Youngest US Counties by Median Age Oldest US Counties by Median Age Cheapest US Counties by Median Home Value Racially Diverse US Counties Counties With Largest Hispanic Population All rankings →

Frequently Asked Questions

DeKalb County, Illinois has a population of 100,512 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 20th-largest county in Illinois. Population density is 159 people per square mile.

The population of DeKalb County has declined 3.6% since 2010 (105,151 → 101,335), a -0.26% annualized rate.

The median household income in DeKalb County, Illinois is $69,022, with mean (average) household income of $87,946 and per-capita income of $35,054. 10.9% of residents live below the federal poverty level.

In DeKalb County, the largest racial and ethnic groups are White (76.3%), Black or African American (7.8%), Hispanic or Latino (1.4%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.

The median age in DeKalb County, Illinois is 32.6 years. Residents are 50.2% female and 49.8% male.

The median home value in DeKalb County is $231,900 and median monthly rent is $1,041. 60.9% of occupied housing units are owner-occupied. The county has 41,499 total housing units, 5.3% of which are vacant.

The largest employment sector in DeKalb County, Illinois is professional, scientific, and management services, employing 27.2% of workers. The unemployment rate is 4.9%.

Chicago is among the largest cities associated with DeKalb County, Illinois, with a population of 2,707,648.