• county
  • FIPS 17187
  • Largest town: Monmouth

Warren County, Illinois

Warren County had 16,217 residents in the Census Vintage 2024 estimate, on 542.3 square miles of land. It ranks 65th of 102 in Illinois by population and 47th by land area.

Population
16,217
#65 of 102 in Illinois · #2,019 in US
Area
542.3 sq mi
#47 of 102 in Illinois · #1,924 in US
Density
30 / sq mi
#72 of 102 in Illinois · #1,930 in US
Median household income
$64,493
#57 of 102 in Illinois · #1,414 in US

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

Warren County within Illinois. Pin: Springfield.

Measure from here

Tools and pages that start from Warren County

Warren County population, land area and income

Warren County had 16,217 residents in the Census Vintage 2024 estimate, on 542.3 square miles of land. It ranks 65th of 102 in Illinois by population and 47th by land area. That works out to 29.9 people per square mile, below the US average of 96.3, and below the national county median.

The median county-equivalent in Illinois has 24,447 residents; Warren County is somewhat smaller.

Its SAIPE 2023 median household income of $64,493 is above the national county median among 3,143 counties with an estimate.

National rank among 3,144

Population

16,217

3144th1st

2019th of 3,144 (US)

Land area

542 sq mi

3144th1st

1924th of 3,144 (US)

Density

29.9 / sq mi

3144th1st

1930th of 3,144 (US)

Median household income

$64,493

3143rd1st

1414th of 3,143 (US)

Rank within Illinois (102)

Population

16,217

102nd1st

65th of 102 (IL)

Land area

542 sq mi

102nd1st

47th of 102 (IL)

Density

29.9 / sq mi

102nd1st

72nd of 102 (IL)

Median household income

$64,493

102nd1st

57th of 102 (IL)

How Warren County's population changed since 2020

Warren County lost 615 residents between the July 2020 and July 2024 estimates, a drop of 3.7%. That ranks 92nd 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, Warren County recorded 847 births and 915 deaths, a natural change of -68. Net international migration added +163 and net domestic migration, people moving to or from other US counties, came to -727. The largest single component was domestic migration, which removed 727 people.

16.8k202016.6k202116.4k202216.2k202316.2k2024
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
847
Deaths
915
Net international migration
+163
Net domestic migration
-727
Change, July 2023 to July 2024
-7

Where Warren County is

The Census internal point of Warren County is at 40.850400, -90.620200. It sits in UTM zone 15N. The map shades Illinois's 102 county-equivalents by population change from 2020 to 2024, darker for faster growth, with Warren 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: Warren County internal point. Dark pin: Springfield.

Internal point

Decimal
40.850400, -90.620200
DMS
40°51'1.44"N 90°37'12.72"W
UTM
15N 700605.1E 4524876.1N
Geohash
9zr83us6u
Plus code
86GFV92H+5W

Towns in Warren County

One incorporated place of 1,000+ people has residents in Warren County, 8,639 people together, or 53% of the county. Each figure counts only the part of the town inside Warren County; towns marked "part" extend into another county. The largest is Monmouth with 8,639.

  1. 01Monmouth8,639
Census Vintage 2024 subcounty estimates, county parts of incorporated places (SUMLEV 157).

Counties bordering Warren County

The Census 2024 county adjacency file lists 5 neighbors for Warren County. The most populous is Knox County, IL, with 48,716 residents. Distances run between Census internal points in a straight line.

Distance to Springfield and the nearest big city

Springfield is 89.8 miles SE of Warren County's internal point in a straight line. The nearest place of 100,000 or more is Davenport, IA (population 100,938), 48.8 miles away. The nearest place of 10,000 or more is Galesburg, IL (population 29,289), 14.5 miles away.

Warren County FIPS code

The FIPS code of Warren County is 17187: state code 17 for Illinois plus county code 187. Use it as text, with the leading zero, when joining Census, BLS, or CDC county tables. SAIPE lists its 2023 median household income as $64,493.

Questions people ask

What is the population of Warren County, Illinois?

The Census Vintage 2024 estimate for July 1, 2024 is 16,217. That is down 615 people (3.7%) from the July 2020 estimate of 16,832.

What is the FIPS code of Warren County?

17187. The first two digits (17) are Illinois; the last three (187) identify the county.

What is the largest town in Warren County?

Monmouth, with 8,639 residents inside Warren County in 2024.

Which counties border Warren County?

5 county-equivalents border it in the Census 2024 adjacency file: Knox County, IL; Fulton County, IL; McDonough County, IL; Mercer County, IL; Henderson 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.