12,543 people (2024 Census estimate, −3.9% since 2020)
539 square miles of land · 23 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 Mason County in the area they serve, reporting 7,934 people served in all (a system that crosses county lines counts its whole population).
| HAVANA groundwater · local government · IL1250200 | 2,963 served |
| MASON CITY groundwater · local government · IL1250350 | 2,393 served |
| MANITO groundwater · local government · IL1250300 | 1,552 served |
| SAN JOSE groundwater · local government · IL1254840 | 479 served |
| EASTON groundwater · local government · IL1250100 | 325 served |
| FOREST CITY groundwater · local government · IL1250010 | 222 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 38 people were held in Mason County's jail, in Vera's latest figure (2019), or 471 per 100,000 residents ages 15–64. In 2014 it was about 44.
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 Mason County. School taxes are usually the largest part of a property tax bill.
Spent $16.8 million — $12.5 million to run schools, about $14,391 per student, plus $3 million on buildings and equipment. Money in: $5.4 million local (mostly property tax), $12.4 million state, $3.3 million federal. Long-term debt: $8 million.
Spent $14.4 million — $13.5 million to run schools, about $15,601 per student, plus $399,000 on buildings and equipment. Money in: $5.9 million local (mostly property tax), $8.7 million state, $2 million federal. Long-term debt: $4.3 million.
Spent $13.3 million — $11.5 million to run schools, about $17,704 per student, plus $1.3 million on buildings and equipment. Money in: $6.9 million local (mostly property tax), $6.4 million state, $1.6 million federal. Long-term debt: $1.1 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 Low compared with other U.S. counties. FEMA estimates natural hazards cost Mason County about $12.3 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.
86 bridges in Mason County: 31 in good condition, 52 fair, and 3 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.
| TR 190 over MAIN DITCH · built 1972 | 50 vehicles a day |
| TR 153 over KILLION DITCH · built 1972 | 25 vehicles a day |
| TR 208 over SLEEPY HOLLOW DITCH · built 1986 | 25 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $7.9 million of work in Mason County in fiscal 2025, about $606 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 Mason 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 Mason County built: brayden.ozark@gmail.com.
More of Illinois: the state government and every county in Illinois.
Nearby counties: Menard County (16 mi) · Fulton County (22 mi) · Cass County (25 mi) · Tazewell County (28 mi) · Logan County (30 mi) · Sangamon County (36 mi).