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Monroe County, IL
6 cities and towns and 7 ZIP codes in Monroe County, Illinois.
Population
35,036
Land area
385sq mi
People per sq mi
91
ZIP codes
7
Cities and towns in Monroe County
Monroe County at a glance
- Monroe County is 60% less dense than Illinois as a whole.
- Households here earn a median of $102,880 a year, 23% more than the Illinois figure of $83,390.
- A typical owner-occupied home is valued at $282,100 (7% above Illinois) and median rent is $1,042 a month.
- The biggest population centers are Waterloo (11,129), Columbia (11,127) and Valmeyer (1,090).
Local data for Monroe County, IL
Counts from official public data
Housing and community stats
Monroe County, IL, American Community Survey 2020-2024
Median household income
$102,880
Poverty rate
5.0%
Median home value
$282,100
Prices +6.5% in a year
Median rent
$1,042/mo
Homeownership
84.7%
Bachelor's or higher
38.7%
Median age
43.2
Average commute
28.3 min
Largest reported origins and ancestries: German Americans (14,275), Irish Americans (4,618), Italian Americans (1,400).
Economy and federal money
Jobs, income, federal spending and pandemic loans
Unemployment rate
2.6%
Sep 2026, -0.6 pts in a year
Average annual pay
$51,694
8,577 jobs, 2025
Income per person
$77,807
BEA, 2024
Federal spending
$257M
FY 2026, $7,342 per person
PPP loans
$65.9M
1,321 loans, 9,129 jobs reported
Campaign donations
$267K
Itemized, 2026 cycle
How people get to work
Monroe County, IL, workers 16 and older. American Community Survey 5-year estimates
- Drove alone79.7%
- Carpooled5.7%
- Public transit0.0%
- Walked1.5%
- Bicycle0.0%
- Taxi, ride-hailing, motorcycle or other0.5%
- Worked from home12.6%
Average one-way commute: 28.3 minutes for people who do not work from home.
Environment and hazard risk
Monroe County, IL, from FEMA, NOAA and EPA
Natural hazard risk
Very Low
Top: heat wave
Storm events since 1996
387
Most often hail
Flood insurance policies
135
0.9% of homes, county
July high / Jan low
88° / 22°F
43.6 inches of rain a year
Hazards, floods and storm historyCheck a flood zone4 historic places
Health statistics
Share of adults in Monroe County, IL, CDC PLACES estimates
Obesity
35.5%
U.S. 33.3% +2.2 pts
Diabetes
10.1%
U.S. 12.1% -2.0 pts
Smoking
11.3%
U.S. 12.8% -1.5 pts
Uninsured (18-64)
5.6%
U.S. 11.1% -5.5 pts
Cities, towns and ZIP codes in Monroe County
Population shown
Frequently asked questions
- What is the largest city in Monroe County, IL?
- Waterloo is the largest city or town in Monroe County, with about 11,129 residents.
- How many ZIP codes are in Monroe County?
- Monroe County includes 7 ZIP Code Tabulation Areas, including 62236, 62244, 62248, 62256, 62279.
- What is the population of Monroe County, IL?
- About 35,036 people live in Monroe County, based on American Community Survey 5-year estimates.
- What counties border Monroe County?
- Monroe County borders St. Louis County, MO, St. Clair County, Jefferson County, MO, Randolph County, Ste. Genevieve County, MO.
Source: U.S. Census Bureau (TIGER/Line boundaries, American Community Survey) · Data as of 12/31/2023