21,150 people (2024 Census estimate, −1.6% since 2020)
370 square miles of land · 57 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.
4 active community water systems list Jersey County in the area they serve, reporting 21,683 people served in all (a system that crosses county lines counts its whole population).
| JERSEY RWC buys surface water · private · IL0835300 | 12,750 served |
| IL AMERICAN-JERSEYVILLE groundwater · local government · IL0830250 | 8,412 served |
| NEW PIASA CHAUTAUQUA PWS buys surface water · private · IL0830010 | 335 served |
| FIELDON buys groundwater · local government · IL0830150 | 186 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 27 people were held in Jersey County's jail, in Vera's latest figure (2019), or 194 per 100,000 residents ages 15–64. In 2014 it was about 24.
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.
1 school district has its office in Jersey County. School taxes are usually the largest part of a property tax bill.
Spent $43.7 million — $36.3 million to run schools, about $14,943 per student, plus $5.7 million on buildings and equipment. Money in: $18.9 million local (mostly property tax), $20.3 million state, $5.5 million federal. Long-term debt: $31.5 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 Jersey County about $10.8 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.
113 bridges in Jersey County: 64 in good condition, 43 fair, and 6 poor (5.3%). “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.
| ILL 100 over ELSAH CREEK · built 1961 | 4,150 vehicles a day |
| ILL 100 over DRAINS TO EAGLE LAKE · built 1938 | 775 vehicles a day |
| TR 187 over LITTLE PIASA CK · built 1972 | 500 vehicles a day |
| FAS 774 over OTTER CREEK · built 1978 | 225 vehicles a day |
| TR 150C over BRANCH LITTLE PIASA · built 1975 | 150 vehicles a day |
| TR 195 over MILL CREEK · built 1977 | 100 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $7.7 million of work in Jersey County in fiscal 2025, about $359 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 Jersey 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 Jersey County built: brayden.ozark@gmail.com.
More of Illinois: the state government and every county in Illinois.
Nearby counties: Calhoun County (17 mi) · Greene County (19 mi) · Macoupin County (27 mi) · St. Charles County, MO (27 mi) · Madison County (30 mi) · St. Louis County, MO (31 mi).