165,461 people (2024 Census estimate, +1.0% since 2020)
718 square miles of land · 230 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.
20 active community water systems list Rock County in the area they serve, reporting 125,455 people served in all (a system that crosses county lines counts its whole population).
| JANESVILLE WATER UTILITY groundwater · local government · WI1540127 | 64,415 served |
| BELOIT CITY OF groundwater · local government · WI1540112 | 36,677 served |
| EVANSVILLE WATERWORKS groundwater · local government · WI1540047 | 5,703 served |
| MILTON WATERWORKS groundwater · local government · WI1540130 | 5,588 served |
| EDGERTON WATERWORKS groundwater · local government · WI1540119 | 5,512 served |
| CLINTON WATERWORKS groundwater · local government · WI1540114 | 2,119 served |
| ORFORDVILLE WATERWORKS groundwater · local government · WI1540132 | 1,475 served |
| ROCKVALE MHP groundwater · private · WI1540126 | 1,200 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 357 people were held in Rock County's jail, in Vera's latest figure (2025). In 2020 it was about 245.
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.
8 school districts have their office in Rock County. School taxes are usually the largest part of a property tax bill.
Spent $152.3 million — $134.3 million to run schools, about $14,077 per student, plus $10 million on buildings and equipment. Money in: $50.5 million local (mostly property tax), $92.6 million state, $21.9 million federal. Long-term debt: $43.3 million.
Spent $110.4 million — $92.6 million to run schools, about $17,936 per student, plus $3.1 million on buildings and equipment. Money in: $12.3 million local (mostly property tax), $85.1 million state, $22.2 million federal. Long-term debt: $28.4 million.
Spent $53.1 million — $44.8 million to run schools, about $13,088 per student, plus $2.1 million on buildings and equipment. Money in: $24.4 million local (mostly property tax), $32.2 million state, $4.6 million federal. Long-term debt: $52.6 million.
Spent $32.1 million — $27.1 million to run schools, about $14,039 per student, plus $1.4 million on buildings and equipment. Money in: $14 million local (mostly property tax), $17.9 million state, $3.5 million federal. Long-term debt: $36.2 million.
Spent $24.4 million — $21 million to run schools, about $12,885 per student, plus $860,000 on buildings and equipment. Money in: $10.2 million local (mostly property tax), $12.9 million state, $2.6 million federal. Long-term debt: $22.2 million.
Spent $27.4 million — $24.8 million to run schools, about $15,541 per student, plus $247,000 on buildings and equipment. Money in: $10.1 million local (mostly property tax), $18.2 million state, $2.6 million federal. Long-term debt: $30 million.
Spent $30.8 million — $16.4 million to run schools, about $15,451 per student, plus $12.8 million on buildings and equipment. Money in: $13.8 million local (mostly property tax), $11.1 million state, $2.2 million federal. Long-term debt: $31.3 million.
Spent $15 million — $12.7 million to run schools, about $14,834 per student, plus $399,000 on buildings and equipment. Money in: $6.6 million local (mostly property tax), $8.8 million state, $1.4 million federal. Long-term debt: $12.2 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 Rock County about $73.3 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.
304 bridges in Rock County: 168 in good condition, 123 fair, and 13 poor (4.3%). “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.
| USH 51-CENTER AVE over UNION PACIFIC RR · built 1982 | 14,600 vehicles a day |
| STH 213-4TH ST over ROCK RIVER · built 1962 | 5,700 vehicles a day |
| CTH N over OTTER CREEK · built 1964 | 1,461 vehicles a day |
| CTH J over TURTLE CREEK OVERFLOW · built 1953 | 1,036 vehicles a day |
| LRD LATHERS RD over TURTLE CREEK · built 1887 | 474 vehicles a day |
| LRD CREEK RD over TURTLE CREEK · built 1957 | 398 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $32.7 million of work in Rock County in fiscal 2025, about $200 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 Wisconsin 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 Rock 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 Rock County built: brayden.ozark@gmail.com.
More of Wisconsin: the state government and every county in Wisconsin.
Nearby counties: Winnebago County, IL (23 mi) · Green County (27 mi) · Walworth County (27 mi) · Boone County, IL (27 mi) · Jefferson County (28 mi) · Dane County (32 mi).