Monroe County, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 40th-largest in Illinois
The population of Monroe County, Illinois is 34,969 as of the 2023 American Community Survey, making it the 40th-largest county in Illinois. The median household income is $101,635, the median home value is $265,600, and the median age is 42.5.
The population of Monroe County has grown 5.8% since 2010 (33,051 → 34,969), a +0.40% annualized rate.
34,969
Population
+0.40%
Annual growth
91
People / sq mi
$101,635
Median Income
$265,600
Median Home Value
Monroe County covers 385 sq mi of land at 90.8 people per square mile.
About Monroe County, IL
What sets Monroe County apart is money: median household income runs $101,635, above the US median of $78,538. Monroe County is a county in Illinois with a population of 34,969. It ranks #40 among counties in Illinois by population.
Earnings sit at the high end: a median household income of $101,635, above the US median of $78,538. Very few residents live in poverty — 3.7%, below the national 12.4%. Home values run above average at $265,600, with typical rent around $996.
Degree attainment is near the top of the range for US counties: 38.2% of adults 25+ hold a bachelor’s, above the 35.0% national rate. A solid 11.6% of workers are based at home, below the national 14.0%, and the average commute runs about 28 minutes each way.
Taken together, the income and housing figures place Monroe County firmly in the higher-cost, higher-earning tier of US counties — a profile that tends to track dense job markets and competitive housing.
Monroe County Population History (2010-2024)
The county of Monroe County had a population of 33,051 in 2010 and 34,969 in 2024, a 5.8% growth over 14 years. The peak was 35,144 in 2023. Average annual growth rate: 0.40%.
34,969
Population (2024)
33,051
Population (2010)
35,144
Peak (2023)
0.40%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 33,051 |
| 2011 | 33,273 |
| 2012 | 33,320 |
| 2013 | 33,523 |
| 2014 | 33,608 |
| 2015 | 33,811 |
| 2016 | 34,037 |
| 2017 | 34,261 |
| 2018 | 34,446 |
| 2019 | 34,738 |
| 2020 | 34,953 |
| 2021 | 35,007 |
| 2022 | 35,107 |
| 2023 | 35,144 |
| 2024 | 34,969 |
Race & Ethnicity
| White | 96.1% |
| Black or African American | 0.6% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 0.5% |
| Two or More Races | 0.0% |
Age & Sex
42.5
Median Age
49.6%
Female
50.4%
Male
18.9%
Age 65+
Age Distribution
Children (under 15): 18.1% · Seniors (65+): 18.9%
Income & Poverty
| Median household income | $101,635+$19,933 vs state |
| Mean household income | $122,572 |
| Per-capita income | $49,438 |
| Poverty rate | 3.7%-4.5% vs state |
| Unemployment rate | 1.4% |
| Employment-to-population | 66.9% |
Top Industries by Employment
The largest employment sector in Monroe County is professional & business services, accounting for 23.2% of workers.
How residents commute
0.0%
Drive alone
1.2%
Carpool
81.1%
Public transit
11.6%
Work from home
28.3 min
Avg commute
Housing
$265,600+$15,100 vs state
Median home value
$996
Median rent
83.8%
Homeownership rate
14,665
Total housing units
94.3%
Occupied
5.7%
Vacant
16.2%
Renter-occupied
Social & access
97.8%
With health insurance
93.7%
With broadband internet
43.7%
Foreign-born
8.5%
Veterans (18+)
10.7%
With a disability
98.2%
Speak language other than English at home
Education
95.8%
High School+
38.2%
Bachelor's+
Largest cities in Illinois
Other counties in Illinois
Part of Illinois
Metro areas in Illinois
County rankings
Frequently Asked Questions
Monroe County, Illinois has a population of 34,969 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 40th-largest county in Illinois. Population density is 91 people per square mile.
The population of Monroe County has grown 5.8% since 2010 (33,051 → 34,969), a +0.40% annualized rate.
The median household income in Monroe County, Illinois is $101,635, with mean (average) household income of $122,572 and per-capita income of $49,438. 3.7% of residents live below the federal poverty level.
In Monroe County, the largest racial and ethnic groups are White (96.1%), Black or African American (0.6%), Hispanic or Latino (0.5%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Monroe County, Illinois is 42.5 years. Residents are 49.6% female and 50.4% male.
The median home value in Monroe County is $265,600 and median monthly rent is $996. 83.8% of occupied housing units are owner-occupied. The county has 14,665 total housing units, 5.7% of which are vacant.
The largest employment sector in Monroe County, Illinois is professional, scientific, and management services, employing 23.2% of workers. The unemployment rate is 1.4%.
Chicago is among the largest cities associated with Monroe County, Illinois, with a population of 2,707,648.
Monroe County, IL Climate
Monroe County, IL has an average annual temperature of 12.7°C (55°F) and receives about 1016 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
12.7°C
Avg Temp
1016
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -1° / 29° | 52 mm |
| February | 1° / 34° | 59 mm |
| March | 7° / 44° | 96 mm |
| April | 13° / 55° | 93 mm |
| May | 18° / 64° | 104 mm |
| June | 23° / 73° | 91 mm |
| July | 25° / 77° | 95 mm |
| August | 24° / 76° | 84 mm |
| September | 20° / 69° | 89 mm |
| October | 14° / 57° | 74 mm |
| November | 7° / 45° | 95 mm |
| December | 1° / 34° | 84 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit Monroe County, IL
The most comfortable months to visit Monroe County, IL are typically September, June and August, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 31°C high). The coldest is January (near -6°C low). May is usually the wettest month.
Where to stay near Monroe County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.