County · Illinois
Monroe County, Illinois
Monroe County, Illinois. Monroe County had 34,840 residents in 2025 by the Census Bureau's estimate, down 0.3% since 2020, in line with Illinois (−0.8%). It holds 7 places (7 cities, villages and boroughs) and 7 census tracts. GEOID 17133.
Monroe County is one of the 15 counties of the St. Louis, MO-IL metropolitan statistical area (the Census Bureau's July 2023 delineation).
Residents, July 2025 estimate
34,840
Census Bureau estimate (no margin published)
2020 Census count: 34,962 · ACS 2020-2024: 35,036
Median household income
$102,880
±$5,432 (90% margin)
Illinois: $83,390
Median home value
$282,100
±$13,470 (90% margin)
Illinois: $263,300
Median gross rent
$1,042
±$61 (90% margin)
Illinois: $1,274
How many people live in Monroe County, and is it growing?
The 2020 Census counted 34,962 residents in Monroe County. The Census Bureau estimates 34,840 for July 1, 2025, down 0.3% since 2020, in line with Illinois (−0.8%). The 2020-2024 American Community Survey puts the population at 35,036 over 385 square miles of land.
| Measure | Monroe County | Illinois | Change since 2015-2019 |
|---|---|---|---|
| Total population | 35,036 | 12,694,798 | +868 |
| Households | 13,851±271 | 5,036,449 | no clear change |
| Average household size | 2.51±0.05 | 2.46 | no clear change |
| Housing units | 14,759±32 | 5,457,452 | +578 |
Monroe County's population since 2000
From 27,619 in 2000 to 34,840 in 2025: up 26.1%. The 2000, 2010 and 2020 figures are census counts. The 2005 figure is the Census Bureau's intercensal estimate, revised to fit the 2000 and 2010 counts and drawn on 2010 boundaries; 2015 and 2025 are July 1 estimates made from the census before them.
Source: The 2000, 2010 and 2020 Census counts and the Census Bureau's population estimates (intercensal 2000-2010, Vintage 2020, Vintage 2025) · Census population estimates
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); PEP Vintage 2025 (CO-EST2025); 2020 Census · Check it at data.census.gov
What cities and towns are in Monroe County?
Monroe County holds 7 places: 7 cities, villages and boroughs (incorporated places). The largest is Waterloo with 11,132 residents (2025 estimate). Places that cross a county line are listed with the share of their 2020 residents who live in this county.
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 place-by-county parts · Check it at data.census.gov
Who lives in Monroe County?
The median resident of Monroe County is 43.2 years old; 21.8% are under 18 and 19.7% are 65 or older. The largest group is non-Hispanic white residents at 95.0%, then Hispanic or Latino residents (of any race) at 1.9%. 1.2% of residents were born outside the United States.
| Measure | Monroe County | Illinois | Change since 2015-2019 |
|---|---|---|---|
| Median age | 43.2±0.5 | 39.0 | +1.2 |
| Under 18 years | 21.8%±0.2 pts | 21.8% | – |
| 65 years and over | 19.7%±0.2 pts | 17.0% | – |
| Hispanic or Latino (any race) | 1.9% | 18.8% | +0.4 pts |
| White alone, not Hispanic | 95.0%±0.3 pts | 58.1% | −1.3 pts |
| Black or African American alone, not Hispanic | 0.6%±0.2 pts | 13.3% | +0.4 pts |
| Asian alone, not Hispanic | 0.6%±0.2 pts | 5.9% | −0.7 pts |
| American Indian and Alaska Native alone, not Hispanic | 0.1%±0.1 pts | 0.1% | – |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0%±0.1 pts | 0.0% | – |
| Two or more races, not Hispanic | 1.6%±0.4 pts | 3.4% | – |
| Some other race alone, not Hispanic | 0.2%±0.2 pts | 0.4% | – |
| Born outside the United States | 1.2%±0.3 pts | 14.7% | −0.7 pts |
| Speak a language other than English at home (age 5+) | 2.1%±0.5 pts | 24.0% | – |
| Civilian veterans (age 18+) | 8.7%±1.2 pts | 4.8% | – |
| With a disability | 10.6%±1.1 pts | 12.1% | – |
| No health insurance coverage | 2.5%±0.5 pts | 6.9% | no clear change |
| High school graduate or higher (age 25+) | 96.0%±1.1 pts | 90.5% | – |
| Bachelor's degree or higher (age 25+) | 38.7%±2.5 pts | 37.8% | +3.7 pts |
| Graduate or professional degree (age 25+) | 13.7%±1.6 pts | 15.3% | – |
| Moved from another state in the past year | 0.9%±0.4 pts | 1.6% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profiles DP02, DP05) · Check it at data.census.gov
What do households in Monroe County earn?
Half of Monroe County's 13,851 households earn less than $102,880 a year (±$5,432), against $83,390 in Illinois. In 2015-2019 it was $105,528 in 2024 dollars; the margins of error cannot tell the two periods apart. 5.0% of residents live below the poverty line.
| Measure | Monroe County | Illinois | Change since 2015-2019 |
|---|---|---|---|
| Median household income | $102,880±$5,432 | $83,390 | no clear change |
| Mean household income | $123,402±$5,415 | $115,638 | – |
| Per capita income | $49,605±$1,904 | $46,406 | no clear change |
| People below the poverty line | 5.0%±1.1 pts | 11.8% | no clear change |
| Children under 18 below the poverty line | 5.2%±2.2 pts | 15.1% | – |
| Households receiving SNAP | 4.4%±1.4 pts | 13.8% | – |
| Households with a broadband subscription | 92.7%±1.6 pts | 90.8% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What does housing cost in Monroe County?
Owners occupy 84.7% of Monroe County's occupied homes and renters 15.3%. The median owner-occupied home is valued at $282,100 by its owner (±$13,470). The median renter pays $1,042 a month including utilities, and 39.5% of renters pay 35% or more of their income on rent.
| Measure | Monroe County | Illinois | Change since 2015-2019 |
|---|---|---|---|
| Median home value (owner-occupied) | $282,100±$13,470 | $263,300 | +$22,054 |
| Median gross rent | $1,042±$61 | $1,274 | no clear change |
| Renters paying 35% or more of income on rent | 39.5%±8.4 pts | 39.0% | no clear change |
| Median monthly owner costs, with a mortgage | $1,973±$88 | $1,987 | – |
| Owner-occupied homes | 84.7%±1.6 pts | 67.1% | no clear change |
| Housing units | 14,759±32 | 5,457,452 | +578 |
| Homeowner vacancy rate | 0.9%±0.6 pts | 1.0% | – |
| Rental vacancy rate | 3.4%±3.8 pts | 5.0% | – |
| Single-family detached homes | 83.5%±1.7 pts | 58.2% | – |
| Mobile homes | 1.9%±0.6 pts | 2.3% | – |
| Built 2020 or later | 1.3%±0.6 pts | 0.7% | – |
| Built 1939 or earlier | 9.8%±1.7 pts | 20.2% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP04) · Check it at data.census.gov
How many new homes is Monroe County building?
Builders took permits for 65 new housing units across Monroe County in 2025 (63 single-family), 1.9 per 1,000 residents.
Source: Building Permits Survey, annual county files 2019-2025, U.S. Census Bureau · Census Building Permits Survey
How do people in Monroe County get to work?
79.7% of Monroe County's workers drive alone and 12.6% work from home. The average trip to work takes 28.3 minutes. The unemployment rate in 2020-2024 averaged 1.9%.
| Measure | Monroe County | Illinois | Change since 2015-2019 |
|---|---|---|---|
| In the labor force (age 16+) | 68.3%±1.6 pts | 65.0% | – |
| Unemployment rate | 1.9%±0.8 pts | 5.8% | no clear change |
| Drove alone to work | 79.7%±2.2 pts | 65.9% | – |
| Carpooled | 5.7%±1.3 pts | 7.8% | – |
| Public transportation | 0.0%±0.1 pts | 5.8% | – |
| Walked | 1.5%±0.6 pts | 2.8% | – |
| Worked from home | 12.6%±2.0 pts | 15.9% | +6.4 pts |
| Mean travel time to work | 28.3 min±1.2 | 27.8 min | no clear change |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What are Monroe County's census tracts?
Monroe County is divided into 7 census tracts. Among those with a reliable estimate, median household income runs from $77,500 (Tract 6001.03) to $136,113 (Tract 6001.04).
| Tract 6001.0217133600102 | 4,654±333 | $112,838 |
|---|---|---|
| Tract 6001.0317133600103 | 3,435±429 | $77,500 |
| Tract 6001.0417133600104 | 5,076±508 | $136,113 |
| Tract 6004.0117133600401 | 7,761±503 | $100,845 |
| Tract 6004.0217133600402 | 4,867±432 | $96,613 |
| Tract 6005.0117133600501 | 6,568±556 | $101,972 |
| Tract 6005.0217133600502 | 2,675±335 | $98,182 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) · Check it at data.census.gov
How does Monroe County compare with Illinois's other counties?
| Measure | Rank |
|---|---|
| Population | 40th of 102 |
| Growth 2020-2025 | 21st of 102 |
| Residents per square mile | 27th of 102 |
| Median household income | 7th of 102 |
| Median home value | 8th of 102 |
| Median gross rent | 14th of 102 |
| Poverty rate | 102nd of 102 |
| Bachelor's degree or higher | 6th of 102 |
| Median age | 38th of 102 |
Source: PlainCities ranks from the American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) and PEP Vintage 2025 · How ranks are computed
How these figures are made: methodology and release checks · reading a margin of error · every state · corrections
Not on this page: crime, weather and schools for Monroe County are other agencies' records. Crime: the FBI's Crime Data Explorer · climate: NOAA's U.S. Climate Normals · schools: the National Center for Education Statistics' school search.