36,107 people (2024 Census estimate, −2.4% since 2020)
571 square miles of land · 63 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.
13 active community water systems list Jefferson County in the area they serve, reporting 35,777 people served in all (a system that crosses county lines counts its whole population).
| MOUNT VERNON buys surface water · local government · IL0810300 | 15,793 served |
| NORTHEAST MOUNT VERNON WATER COMPANY buys surface water · private · IL0810010 | 5,483 served |
| WOODLAWN buys surface water · local government · IL0810450 | 3,587 served |
| DIX-KELL WATER COMMSSION buys surface water · local government · IL0815100 | 1,972 served |
| BELLE RIVE buys surface water · local government · IL0810050 | 1,930 served |
| WALTONVILLE buys surface water · local government · IL0810400 | 1,901 served |
| BLUFORD buys surface water · local government · IL0810100 | 1,880 served |
| BIG MUDDY RIVER CC buys surface water · state · IL0810020 | 1,771 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 170 people were held in Jefferson County's jail, in Vera's latest figure (2023), or 764 per 100,000 residents ages 15–64. In 2018 it was about 181.
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.
13 school districts have their office in Jefferson County. School taxes are usually the largest part of a property tax bill.
Spent $33.2 million — $28.4 million to run schools, about $18,791 per student, plus $3.2 million on buildings and equipment. Money in: $8.4 million local (mostly property tax), $17.2 million state, $10.3 million federal. Long-term debt: $6.8 million.
Spent $26.8 million — $23.4 million to run schools, about $19,317 per student, plus $1.5 million on buildings and equipment. Money in: $12.6 million local (mostly property tax), $13.7 million state, $2.3 million federal. Long-term debt: $14.5 million.
Spent $7.1 million — $6.2 million to run schools, about $16,401 per student, plus $450,000 on buildings and equipment. Money in: $2 million local (mostly property tax), $4.3 million state, $1.1 million federal. Long-term debt: $3 million.
Spent $5.3 million — $4.5 million to run schools, about $13,688 per student, plus $480,000 on buildings and equipment. Money in: $912,000 local (mostly property tax), $3.7 million state, $880,000 federal. Long-term debt: $143,000.
Spent $5.6 million — $4.9 million to run schools, about $16,145 per student, plus $415,000 on buildings and equipment. Money in: $1.8 million local (mostly property tax), $3.7 million state, $774,000 federal.
Spent $3.8 million — $3.6 million to run schools, about $13,062 per student, plus $26,000 on buildings and equipment. Money in: $1 million local (mostly property tax), $2.5 million state, $681,000 federal. Long-term debt: $369,000.
Spent $5.9 million — $3.1 million to run schools, about $13,243 per student, plus $2.5 million on buildings and equipment. Money in: $988,000 local (mostly property tax), $2.4 million state, $712,000 federal. Long-term debt: $2.8 million.
Spent $3.4 million — $3 million to run schools, about $13,518 per student, plus $202,000 on buildings and equipment. Money in: $936,000 local (mostly property tax), $2.3 million state, $734,000 federal. Long-term debt: $179,000.
And 5 more.
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: Relatively Low compared with other U.S. counties. FEMA estimates natural hazards cost Jefferson County about $34.1 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively High; social vulnerability: Relatively Moderate.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
259 bridges in Jefferson County: 114 in good condition, 124 fair, and 21 poor (8.1%). “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.
| FAP-821 (ILL-15) over FAI-57 · built 1968 | 18,800 vehicles a day |
| I 57 NB over DODDS CREEK · built 1965 | 18,100 vehicles a day |
| I 57 SB over DODDS CREEK · built 1965 | 18,100 vehicles a day |
| I 64 EB over FAP-724 (ILL-37) · built 1972 | 5,500 vehicles a day |
| I 64 WB over CASEY FK & UN PAC RR · built 1972 | 5,500 vehicles a day |
| I 64 EB over CASEY FK & UN PAC RR · built 1972 | 5,500 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $26.5 million of work in Jefferson County in fiscal 2025, about $713 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 Jefferson 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 Jefferson County built: brayden.ozark@gmail.com.
More of Illinois: the state government and every county in Illinois.
Nearby counties: Franklin County (21 mi) · Marion County (24 mi) · Hamilton County (26 mi) · Washington County (27 mi) · Wayne County (28 mi) · Perry County (28 mi).