283,790 people (2024 Census estimate, −0.4% since 2020)
513 square miles of land · 553 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.
28 active community water systems list Winnebago County in the area they serve, reporting 241,173 people served in all (a system that crosses county lines counts its whole population).
| ROCKFORD groundwater · local government · IL2010300 | 147,051 served |
| NORTH PARK PWD groundwater · local government · IL2015500 | 35,580 served |
| LOVES PARK groundwater · local government · IL2010150 | 23,335 served |
| IL AMERICAN-SOUTH BELOIT buys groundwater · private · IL2010450 | 7,893 served |
| ROCKTON groundwater · local government · IL2010350 | 7,863 served |
| CHERRY VALLEY groundwater · local government · IL2010050 | 4,731 served |
| WINNEBAGO groundwater · local government · IL2010500 | 2,940 served |
| OTTER CREEK LAKE UTILITIES DISTRICT groundwater · local government · IL2015320 | 2,342 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 731 people were held in Winnebago County's jail, in Vera's latest figure (2024), or 420 per 100,000 residents ages 15–64. In 2019 it was about 807.
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.
11 school districts have their office in Winnebago County. School taxes are usually the largest part of a property tax bill.
Spent $641.5 million — $521.8 million to run schools, about $19,016 per student, plus $100.7 million on buildings and equipment. Money in: $164.5 million local (mostly property tax), $379.9 million state, $127.8 million federal. Long-term debt: $179.3 million.
Spent $142.2 million — $130.4 million to run schools, about $21,101 per student, plus $6.8 million on buildings and equipment. Money in: $52.8 million local (mostly property tax), $79.1 million state, $16.2 million federal. Long-term debt: $6.6 million.
Spent $38.9 million — $34.6 million to run schools, about $18,309 per student, plus $3.3 million on buildings and equipment. Money in: $22.9 million local (mostly property tax), $17 million state, $1.8 million federal. Long-term debt: $19 million.
Spent $25.2 million — $23.9 million to run schools, about $13,855 per student, plus $765,000 on buildings and equipment. Money in: $16.3 million local (mostly property tax), $12.7 million state, $1.8 million federal. Long-term debt: $3.1 million.
Spent $23.6 million — $22.1 million to run schools, about $13,795 per student, plus $622,000 on buildings and equipment. Money in: $10.4 million local (mostly property tax), $12.4 million state, $2 million federal. Long-term debt: $2.9 million.
Spent $25 million — $22.8 million to run schools, about $17,709 per student, plus $761,000 on buildings and equipment. Money in: $13.4 million local (mostly property tax), $11.6 million state, $1.9 million federal. Long-term debt: $13.2 million.
Spent $18.8 million — $15.2 million to run schools, about $16,785 per student, plus $3.4 million on buildings and equipment. Money in: $5.9 million local (mostly property tax), $11 million state, $3.2 million federal. Long-term debt: $5.8 million.
Spent $15.3 million — $14.1 million to run schools, about $15,721 per student, plus $362,000 on buildings and equipment. Money in: $7.3 million local (mostly property tax), $7.5 million state, $525,000 federal. Long-term debt: $2.3 million.
And 3 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 Moderate compared with other U.S. counties. FEMA estimates natural hazards cost Winnebago County about $121.6 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively High; social vulnerability: Relatively Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
465 bridges in Winnebago County: 142 in good condition, 291 fair, and 32 poor (6.9%). “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.
| I-39 SB over HARRISON AVE · built 1963 | 25,450 vehicles a day |
| I-39 NB over HARRISON AVE · built 1963 | 21,150 vehicles a day |
| ILL 251 S B over UP RR · built 1967 | 13,000 vehicles a day |
| ILL 251 N B over UP RR · built 1967 | 13,000 vehicles a day |
| AUBURN ST. over KENT CREEK · built 1930 | 12,400 vehicles a day |
| ROSCOE RD over ROCK RIVER · built 1967 | 10,700 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $54.5 million of work in Winnebago County in fiscal 2025, about $191 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 Winnebago 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 Winnebago County built: brayden.ozark@gmail.com.
More of Illinois: the state government and every county in Illinois.
Nearby counties: Boone County (17 mi) · Ogle County (22 mi) · Rock County, WI (23 mi) · Stephenson County (26 mi) · Green County, WI (33 mi) · McHenry County (36 mi).