• county
  • FIPS 17037
  • Largest town: DeKalb

DeKalb County, Illinois

DeKalb County had 101,335 residents in the Census Vintage 2024 estimate, on 631.3 square miles of land. It ranks 19th of 102 in Illinois by population and 30th by land area.

Population
101,335
#19 of 102 in Illinois · #616 in US
Area
631.3 sq mi
#30 of 102 in Illinois · #1,520 in US
Density
161 / sq mi
#18 of 102 in Illinois · #664 in US
Median household income
$69,439
#41 of 102 in Illinois · #1,044 in US

Census Vintage 2024 estimates · SAIPE 2023 income · 2024 Gazetteer land area

DeKalb County within Illinois. Pin: Springfield.

Measure from here

Tools and pages that start from DeKalb County

DeKalb County population, land area and income

DeKalb County had 101,335 residents in the Census Vintage 2024 estimate, on 631.3 square miles of land. It ranks 19th of 102 in Illinois by population and 30th by land area. That works out to 160.5 people per square mile, 1.7 times the US average of 96.3, and in the top quarter nationally.

The median county-equivalent in Illinois has 24,447 residents, so DeKalb County is 4.1 times that size.

Its SAIPE 2023 median household income of $69,439 is above the national county median among 3,143 counties with an estimate.

National rank among 3,144

Population

101,335

3144th1st

616th of 3,144 (US)

Land area

631 sq mi

3144th1st

1520th of 3,144 (US)

Density

160.5 / sq mi

3144th1st

664th of 3,144 (US)

Median household income

$69,439

3143rd1st

1044th of 3,143 (US)

Rank within Illinois (102)

Population

101,335

102nd1st

19th of 102 (IL)

Land area

631 sq mi

102nd1st

30th of 102 (IL)

Density

160.5 / sq mi

102nd1st

18th of 102 (IL)

Median household income

$69,439

102nd1st

41st of 102 (IL)

How DeKalb County's population changed since 2020

DeKalb County gained 967 residents between the July 2020 and July 2024 estimates, a rise of 1.0%. That ranks 7th of 102 in Illinois for growth. The median Illinois county changed by -1.7%, and the state as a whole by -0.7%.

Since the April 2020 estimates base, DeKalb County recorded 4,431 births and 3,638 deaths, a natural change of +793. Net international migration added +1,558 and net domestic migration, people moving to or from other US counties, came to -1,584. The largest single component was domestic migration, which removed 1,584 people.

100.4k2020100.6k2021100.6k2022100.7k2023101.3k2024
Census Vintage 2024 county estimates for July 1 of each year. The axis starts above zero so year-to-year changes are visible.

Components of change, April 2020 to July 2024

Births
4,431
Deaths
3,638
Net international migration
+1,558
Net domestic migration
-1,584
Change, July 2023 to July 2024
+674

Where DeKalb County is

The Census internal point of DeKalb County is at 41.894600, -88.769000. It sits in UTM zone 16N. The map shades Illinois's 102 county-equivalents by population change from 2020 to 2024, darker for faster growth, with DeKalb County outlined. Dots are towns of 1,000+ people with residents in it.

Piatt County: -0.3%Hamilton County: -2.2%Williamson County: -0.1%Edgar County: -2.4%Macoupin County: -2.3%Marshall County: -1.3%Putnam County: +0.0%Richland County: -2.8%Washington County: -1.4%Lee County: -1.5%Douglas County: +0.2%Cook County: -1.6%Effingham County: -0.3%Edwards County: -3.6%Cass County: -2.0%Clay County: -3.4%Knox County: -2.2%LaSalle County: -0.9%Cumberland County: -1.3%Warren County: -3.7%Moultrie County: -0.9%Menard County: -2.5%Fayette County: -1.5%Boone County: -0.0%Lawrence County: -3.2%Marion County: -3.2%Champaign County: +3.0%Clark County: -2.4%Ford County: -0.4%Wayne County: -1.4%Logan County: -1.4%Grundy County: +2.5%Jasper County: -1.8%Crawford County: -1.3%McDonough County: -1.7%Clinton County: +0.5%Perry County: -3.0%Montgomery County: -2.2%Henry County: -2.0%Livingston County: -1.2%Scott County: -3.8%Alexander County: -11.2%Bureau County: -2.2%Brown County: +1.1%Mason County: -3.9%Calhoun County: -4.1%Greene County: -4.3%Coles County: -1.4%Kendall County: +8.2%Lake County: +0.7%Mercer County: -2.2%St. Clair County: -2.3%Wabash County: -3.0%Bond County: -1.7%DuPage County: +0.6%Gallatin County: -5.2%Stephenson County: -3.3%McHenry County: +1.9%White County: -3.0%Saline County: -3.9%Christian County: -2.2%Sangamon County: -1.0%Massac County: -3.6%Macon County: -2.9%Johnson County: -0.0%Jo Daviess County: -2.6%Peoria County: -1.0%DeKalb County: +1.0%Pope County: -1.5%De Witt County: -0.9%Schuyler County: -1.7%Fulton County: -3.1%Ogle County: -0.8%Jersey County: -1.6%Iroquois County: -3.3%Kankakee County: -0.9%Rock Island County: -1.1%Pulaski County: -5.8%Kane County: +0.9%Union County: -2.4%Whiteside County: -1.7%Woodford County: -0.3%Carroll County: -1.5%Adams County: -2.3%Hardin County: -2.6%Madison County: -1.0%Hancock County: -3.1%Monroe County: +0.0%Tazewell County: -1.1%Jackson County: -0.1%Vermilion County: -3.9%Randolph County: -0.6%McLean County: +0.5%Morgan County: -2.6%Shelby County: -1.7%Will County: +1.7%Winnebago County: -0.4%Jefferson County: -2.4%Stark County: -2.2%Henderson County: -4.5%Pike County: -2.6%Franklin County: -1.8%
Change 2020 to 2024
  1. < -3.0%
  2. < -2.2%
  3. < -1.4%
  4. < -0.3%
  5. ≥ -0.3%
no data

Orange pin: DeKalb County internal point. Dark pin: Springfield.

Internal point

Decimal
41.894600, -88.769000
DMS
41°53'40.56"N 88°46'8.40"W
UTM
16N 353251.5E 4639586.9N
Geohash
dp2yk48ms
Plus code
86HHV6VJ+RC

Towns in DeKalb County

12 incorporated places of 1,000+ people have residents in DeKalb County, 86,340 people together, or 85% of the county. Each figure counts only the part of the town inside DeKalb County; towns marked "part" extend into another county. The largest is DeKalb with 40,491.

  1. 01DeKalb40,491
  2. 02Sycamore18,968
  3. 03Sandwich (part)7,133
  4. 04Genoa5,514
  5. 05Cortland4,592
  6. 06Hinckley1,976
  7. 07Kirkland1,621
  8. 08Waterman1,543
  9. 09Somonauk (part)1,531
  10. 10Malta1,137
  11. 11Kingston1,095
  12. 12Maple Park (part)739
Census Vintage 2024 subcounty estimates, county parts of incorporated places (SUMLEV 157).

Counties bordering DeKalb County

The Census 2024 county adjacency file lists 8 neighbors for DeKalb County. The most populous is Kane County, IL, with 520,997 residents. Distances run between Census internal points in a straight line.

Distance to Springfield and the nearest big city

Springfield is 153.1 miles SSW of DeKalb County's internal point in a straight line. The nearest place of 100,000 or more is Elgin, IL (population 114,701), 24.9 miles away. The nearest place of 10,000 or more is DeKalb, IL (population 40,491), 2.5 miles away.

DeKalb County FIPS code

The FIPS code of DeKalb County is 17037: state code 17 for Illinois plus county code 037. Use it as text, with the leading zero, when joining Census, BLS, or CDC county tables. SAIPE lists its 2023 median household income as $69,439.

Questions people ask

What is the population of DeKalb County, Illinois?

The Census Vintage 2024 estimate for July 1, 2024 is 101,335. That is up 967 people (1.0%) from the July 2020 estimate of 100,368.

What is the FIPS code of DeKalb County?

17037. The first two digits (17) are Illinois; the last three (037) identify the county.

What is the largest town in DeKalb County?

DeKalb, with 40,491 residents inside DeKalb County in 2024.

Which counties border DeKalb County?

8 county-equivalents border it in the Census 2024 adjacency file: Kane County, IL; McHenry County, IL; Winnebago County, IL; Kendall County, IL; LaSalle County, IL; Boone County, IL; Ogle County, IL; Lee County, IL.

Sources and data as of

Data as of: Census Vintage 2024 population estimates, 2024 Gazetteer land area and internal points, SAIPE 2023 median household income.

  1. 01Census Vintage 2024 county population estimates
  2. 02Census 2024 Gazetteer, counties
  3. 03Census SAIPE 2023 state and county estimates
  4. 04Census Vintage 2024 subcounty population estimates
  5. 05Census 2024 county adjacency file
  6. 06Census 2024 cartographic boundary file, counties (1:5,000,000)

How every number is computed: methodology. Spotted a wrong figure? Report an error.