34,969 people (2024 Census estimate, +0.0% since 2020)
385 square miles of land · 91 people per square mile
“Highest” and “lowest” are just order, not grades: a high rank for poverty or hazard losses means more of it. Each figure's source is in its section below.
6 active community water systems list Monroe County in the area they serve, reporting 27,671 people served in all (a system that crosses county lines counts its whole population).
| COLUMBIA buys surface water · local government · IL1330050 | 11,129 served |
| WATERLOO groundwater · local government · IL1330300 | 10,190 served |
| FOUNTAIN WATER DISTRICT groundwater · local government · IL1330020 | 4,350 served |
| VALMEYER buys groundwater · local government · IL1330250 | 1,233 served |
| HECKER buys surface water · local government · IL1330150 | 429 served |
| MAEYSTOWN buys groundwater · local government · IL1330200 | 340 served |
Source: U.S. EPA Safe Drinking Water Information System (SDWIS), active community systems, . Look up any system's violations and test results with EPA's search using its ID.
About 11 people were held in Monroe County's jail, in Vera's latest figure (2024), or 50 per 100,000 residents ages 15–64. In 2019 it was about 35.
Source: Vera Institute of Justice, Incarceration Trends (built from federal Bureau of Justice Statistics jail surveys). Counties without their own jail, or that share one, may show no figure.
3 school districts have their office in Monroe County. School taxes are usually the largest part of a property tax bill.
Spent $39.6 million — $34.9 million to run schools, about $12,591 per student, plus $1.5 million on buildings and equipment. Money in: $27.8 million local (mostly property tax), $14.5 million state, $2.7 million federal. Long-term debt: $36.7 million.
Spent $28.4 million — $25.8 million to run schools, about $12,981 per student, plus $1.9 million on buildings and equipment. Money in: $19.8 million local (mostly property tax), $11 million state, $1.3 million federal. Long-term debt: $8.8 million.
Spent $5.4 million — $4.8 million to run schools, about $13,651 per student, plus $214,000 on buildings and equipment. Money in: $3.4 million local (mostly property tax), $2.4 million state, $450,000 federal. Long-term debt: $3.7 million.
Source: U.S. Census Bureau, 2023 Annual Survey of School System Finances. Districts are listed by the county of their main office; some serve neighboring counties too.
Source: County Health Rankings & Roadmaps 2025 (University of Wisconsin Population Health Institute), which gathers federal data (CDC, Census, and others); measures cover different recent years. Blank lines aren't reported for small counties.
Overall risk: Very Low compared with other U.S. counties. FEMA estimates natural hazards cost Monroe County about $22.6 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Very High; social vulnerability: Very Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
132 bridges in Monroe County: 79 in good condition, 42 fair, and 11 poor (8.3%). “Poor” means a main part — the deck, the beams, or the supports — is rated 4 or lower on the federal 0–9 scale. It doesn't mean unsafe to drive; unsafe bridges are closed.
| FAI 255 NB/EB over UPRR · built 1984 | 25,850 vehicles a day |
| FAU 9300 over CARR CREEK · built 1995 | 3,750 vehicles a day |
| FAS-1858 (CH-12) over Dennis Hollow · built 1927 | 1,350 vehicles a day |
| MS 6190 (CARL ST) over CREEK · built 1972 | 1,050 vehicles a day |
| GALL RD/ FAU 9345 over CARR CREEK · built 1978 | 675 vehicles a day |
| MAEYSTOWN MSS 1030 over MAEYSTOWN CREEK · built 1941 | 350 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $9.1 million of work in Monroe County in fiscal 2025, about $261 per resident — to the county, cities, schools, hospitals, nonprofits and others.
Source: USAspending.gov, grants by place of performance, fiscal 2025 (Oct. 2024 to Sept. 2025). Search it by county to see each award.
From Grants.gov: posted grants listing county governments as eligible, soonest deadline first; research-only and overseas programs left out; list updated 2026-10-13, refreshed weekly. 62 are open in all. Cities, towns, school districts and nonprofits have their own lists there.
Registration deadlines, early voting and polling places for Illinois are on the federal site vote.gov, which links to the state's official election office.
The budget, property tax rates, audits, local officials and offices for Monroe County come from the county's own records, which we haven't gathered — not gathered, never hidden. See what a full county site looks like, or ask to have Monroe County built: brayden.ozark@gmail.com.
More of Illinois: the state government and every county in Illinois.
Nearby counties: St. Clair County (19 mi) · Jefferson County, MO (20 mi) · Randolph County (25 mi) · St. Louis city, MO (25 mi) · Ste. Genevieve County, MO (27 mi) · St. Louis County, MO (29 mi).