67,064 people (2024 Census estimate, −0.1% since 2020)
420 square miles of land · 160 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.
24 active community water systems list Williamson County in the area they serve, reporting 75,436 people served in all (a system that crosses county lines counts its whole population).
| MARION buys surface water · local government · IL1990550 | 16,855 served |
| HERRIN buys surface water · local government · IL1990400 | 12,747 served |
| LAKE OF EGYPT PWD surface water · local government · IL1995200 | 11,368 served |
| CARTERVILLE buys surface water · local government · IL1990150 | 6,528 served |
| COAL VALLEY PWD buys surface water · local government · IL1995250 | 4,023 served |
| CORINTH PWD buys surface water · local government · IL1995120 | 3,927 served |
| JOHNSTON CITY buys surface water · local government · IL1990500 | 3,509 served |
| PITTSBURG buys surface water · local government · IL1990600 | 2,948 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 161 people were held in Williamson County's jail, in Vera's latest figure (2023), or 387 per 100,000 residents ages 15–64. In 2018 it was about 119.
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.
5 school districts have their office in Williamson County. School taxes are usually the largest part of a property tax bill.
Spent $67.6 million — $49.2 million to run schools, about $13,127 per student, plus $11.2 million on buildings and equipment. Money in: $32.8 million local (mostly property tax), $26 million state, $12.4 million federal. Long-term debt: $19.5 million.
Spent $38.3 million — $30.6 million to run schools, about $12,991 per student, plus $2.7 million on buildings and equipment. Money in: $10.9 million local (mostly property tax), $24.7 million state, $5.1 million federal. Long-term debt: $25.9 million.
Spent $29.5 million — $23.1 million to run schools, about $10,411 per student, plus $2.3 million on buildings and equipment. Money in: $12.7 million local (mostly property tax), $14.1 million state, $6.2 million federal. Long-term debt: $35.1 million.
Spent $18.6 million — $14.3 million to run schools, about $13,113 per student, plus $2.1 million on buildings and equipment. Money in: $5.9 million local (mostly property tax), $11.4 million state, $4 million federal. Long-term debt: $2.8 million.
Spent $6.9 million — $5.9 million to run schools, about $11,990 per student, plus $334,000 on buildings and equipment. Money in: $2.3 million local (mostly property tax), $5 million state, $917,000 federal. Long-term debt: $2.5 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: Relatively Moderate compared with other U.S. counties. FEMA estimates natural hazards cost Williamson County about $52.5 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.
200 bridges in Williamson County: 133 in good condition, 60 fair, and 7 poor (3.5%). “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.
| ILL 13 EB over CRABORCHARD LAKE · built 1964 | 25,600 vehicles a day |
| ILL 13 EB over CRABORCHARD LAKE · built 1964 | 23,500 vehicles a day |
| FAS 903 (CH 2) over INTERSTATE 57 · built 1961 | 6,500 vehicles a day |
| TR 241 (CEDAR GROV over INTERSTATE 57 · built 1961 | 1,750 vehicles a day |
| TR 23 (STIRITZ RD) over INTERSTATE 57 · built 1961 | 1,000 vehicles a day |
| TR 608 over MINE HAULAGE ROAD · built 1978 | 250 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $58.9 million of work in Williamson County in fiscal 2025, about $877 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 Williamson 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 Williamson County built: brayden.ozark@gmail.com.
More of Illinois: the state government and every county in Illinois.
Nearby counties: Franklin County (18 mi) · Johnson County (19 mi) · Saline County (21 mi) · Union County (24 mi) · Jackson County (25 mi) · Pope County (30 mi).