13,320 people (2024 Census estimate, −0.0% since 2020)
344 square miles of land · 39 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 Johnson County in the area they serve, reporting 8,292 people served in all (a system that crosses county lines counts its whole population).
| BURNSIDE PWD buys surface water · local government · IL0875050 | 2,998 served |
| VIENNA surface water · local government · IL0870350 | 1,618 served |
| SHAWNEE CORRECTIONAL CENTER buys surface water · state · IL0870010 | 1,617 served |
| GOREVILLE buys surface water · local government · IL0870200 | 1,068 served |
| VIENNA CORRECTIONAL CENTER surface water · state · IL0875510 | 501 served |
| BELKNAP groundwater · local government · IL0870050 | 490 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 41 people were held in Johnson County's jail, in Vera's latest figure (2019), or 463 per 100,000 residents ages 15–64. In 2014 it was about 28.
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.
6 school districts have their office in Johnson County. School taxes are usually the largest part of a property tax bill.
Spent $9.7 million — $8.9 million to run schools, about $14,296 per student, plus $324,000 on buildings and equipment. Money in: $3.7 million local (mostly property tax), $5.8 million state, $754,000 federal. Long-term debt: $4.3 million.
Spent $6.3 million — $5.6 million to run schools, about $14,005 per student, plus $368,000 on buildings and equipment. Money in: $1.5 million local (mostly property tax), $4.3 million state, $742,000 federal. Long-term debt: $2.1 million.
Spent $7.7 million — $6.7 million to run schools, about $20,823 per student, plus $608,000 on buildings and equipment. Money in: $2.7 million local (mostly property tax), $5.3 million state, $1.1 million federal. Long-term debt: $2.4 million.
Spent $3.5 million — $3.1 million to run schools, about $14,962 per student, plus $247,000 on buildings and equipment. Money in: $724,000 local (mostly property tax), $2.5 million state, $796,000 federal. Long-term debt: $192,000.
Spent $1.6 million — $1.5 million to run schools, about $14,362 per student, plus $34,000 on buildings and equipment. Money in: $339,000 local (mostly property tax), $1.4 million state, $209,000 federal. Long-term debt: $171,000.
Spent $1.1 million — $919,000 to run schools, about $14,823 per student, plus $97,000 on buildings and equipment. Money in: $264,000 local (mostly property tax), $697,000 state, $314,000 federal. Long-term debt: $58,000.
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 Johnson County about $11.9 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively Moderate; social vulnerability: Very High.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
118 bridges in Johnson County: 65 in good condition, 50 fair, and 3 poor (2.5%). “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.
| TR 111 over DUTCHMAN CR. TRIB. · built 1978 | 225 vehicles a day |
| SBI 146 over DUTCHMAN CREEK · built 1930 | 200 vehicles a day |
| FR 870 over WAGON CREEK · built 1967 | 29 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $8.5 million of work in Johnson County in fiscal 2025, about $638 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 Johnson 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 Johnson County built: brayden.ozark@gmail.com.
More of Illinois: the state government and every county in Illinois.
Nearby counties: Williamson County (19 mi) · Pope County (19 mi) · Massac County (19 mi) · Union County (20 mi) · Pulaski County (22 mi) · Saline County (27 mi).