• county
  • FIPS 17081
  • Largest town: Mount Vernon

Jefferson County, Illinois

Jefferson County had 36,107 residents in the Census Vintage 2024 estimate, on 571.2 square miles of land. It ranks 38th of 102 in Illinois by population and 41st by land area.

Population
36,107
#38 of 102 in Illinois · #1,291 in US
Area
571.2 sq mi
#41 of 102 in Illinois · #1,760 in US
Density
63 / sq mi
#38 of 102 in Illinois · #1,264 in US
Median household income
$60,543
#79 of 102 in Illinois · #1,790 in US

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

Jefferson County within Illinois. Pin: Springfield.

Measure from here

Tools and pages that start from Jefferson County

Jefferson County population, land area and income

Jefferson County had 36,107 residents in the Census Vintage 2024 estimate, on 571.2 square miles of land. It ranks 38th of 102 in Illinois by population and 41st by land area. That works out to 63.2 people per square mile, below the US average of 96.3, and above the national county median.

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

Its SAIPE 2023 median household income of $60,543 is below the national county median among 3,143 counties with an estimate.

National rank among 3,144

Population

36,107

3144th1st

1291st of 3,144 (US)

Land area

571 sq mi

3144th1st

1760th of 3,144 (US)

Density

63.2 / sq mi

3144th1st

1264th of 3,144 (US)

Median household income

$60,543

3143rd1st

1790th of 3,143 (US)

Rank within Illinois (102)

Population

36,107

102nd1st

38th of 102 (IL)

Land area

571 sq mi

102nd1st

41st of 102 (IL)

Density

63.2 / sq mi

102nd1st

38th of 102 (IL)

Median household income

$60,543

102nd1st

79th of 102 (IL)

How Jefferson County's population changed since 2020

Jefferson County lost 893 residents between the July 2020 and July 2024 estimates, a drop of 2.4%. That ranks 71st 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, Jefferson County recorded 1,683 births and 2,213 deaths, a natural change of -530. Net international migration added +77 and net domestic migration, people moving to or from other US counties, came to -561. The largest single component was domestic migration, which removed 561 people.

37.0k202036.9k202136.4k202236.3k202336.1k2024
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
1,683
Deaths
2,213
Net international migration
+77
Net domestic migration
-561
Change, July 2023 to July 2024
-224

Where Jefferson County is

The Census internal point of Jefferson County is at 38.300800, -88.924200. 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 Jefferson 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: Jefferson County internal point. Dark pin: Springfield.

Internal point

Decimal
38.300800, -88.924200
DMS
38°18'2.88"N 88°55'27.12"W
UTM
16N 331745.4E 4240941.7N
Geohash
dnbcbkrq7
Plus code
86CH832G+88

Towns in Jefferson County

2 incorporated places of 1,000+ people have residents in Jefferson County, 15,810 people together, or 44% of the county. Each figure counts only the part of the town inside Jefferson County; towns marked "part" extend into another county. The largest is Mount Vernon with 14,162.

  1. 01Mount Vernon14,162
  2. 02Ina1,648
Census Vintage 2024 subcounty estimates, county parts of incorporated places (SUMLEV 157).

Counties bordering Jefferson County

The Census 2024 county adjacency file lists 6 neighbors for Jefferson County. The most populous is Franklin County, IL, with 37,033 residents. Distances run between Census internal points in a straight line.

Distance to Springfield and the nearest big city

Springfield is 109.4 miles NNW of Jefferson County's internal point in a straight line. The nearest place of 100,000 or more is St. Louis, MO (population 279,695), 75.1 miles away. The nearest place of 10,000 or more is Mount Vernon, IL (population 14,162), 1.0 miles away.

Jefferson County FIPS code

The FIPS code of Jefferson County is 17081: state code 17 for Illinois plus county code 081. Use it as text, with the leading zero, when joining Census, BLS, or CDC county tables. SAIPE lists its 2023 median household income as $60,543.

Questions people ask

What is the population of Jefferson County, Illinois?

The Census Vintage 2024 estimate for July 1, 2024 is 36,107. That is down 893 people (2.4%) from the July 2020 estimate of 37,000.

What is the FIPS code of Jefferson County?

17081. The first two digits (17) are Illinois; the last three (081) identify the county.

What is the largest town in Jefferson County?

Mount Vernon, with 14,162 residents inside Jefferson County in 2024.

Which counties border Jefferson County?

6 county-equivalents border it in the Census 2024 adjacency file: Franklin County, IL; Marion County, IL; Perry County, IL; Wayne County, IL; Washington County, IL; Hamilton 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.