142,731 people (2024 Census estimate, −1.1% since 2020)
427 square miles of land · 334 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.
49 active community water systems list Rock Island County in the area they serve, reporting 146,742 people served in all (a system that crosses county lines counts its whole population).
| MOLINE surface water · local government · IL1610450 | 44,500 served |
| ROCK ISLAND surface water · local government · IL1610650 | 39,018 served |
| EAST MOLINE surface water · local government · IL1610250 | 21,374 served |
| ROCK ISLAND ARSENAL, US ARMY surface water · federal · IL1615387 | 7,800 served |
| SILVIS buys surface water · local government · IL1610700 | 7,473 served |
| MILAN groundwater · local government · IL1610400 | 4,945 served |
| COAL VALLEY groundwater · local government · IL1614260 | 3,873 served |
| CARBON CLIFF groundwater · local government · IL1610100 | 2,134 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 189 people were held in Rock Island County's jail, in Vera's latest figure (2023), or 220 per 100,000 residents ages 15–64. In 2018 it was about 265.
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.
9 school districts have their office in Rock Island County. School taxes are usually the largest part of a property tax bill.
Spent $135.1 million — $114.9 million to run schools, about $15,998 per student, plus $17.5 million on buildings and equipment. Money in: $59.1 million local (mostly property tax), $73.4 million state, $19.4 million federal. Long-term debt: $33.4 million.
Spent $154.1 million — $129.5 million to run schools, about $20,881 per student, plus $15 million on buildings and equipment. Money in: $44.2 million local (mostly property tax), $76.1 million state, $27.9 million federal. Long-term debt: $31.8 million.
Spent $56.3 million — $50.9 million to run schools, about $19,587 per student, plus $2.4 million on buildings and equipment. Money in: $19.9 million local (mostly property tax), $35.5 million state, $7.8 million federal. Long-term debt: $35.7 million.
Spent $31.2 million — $26.4 million to run schools, about $14,751 per student, plus $2.8 million on buildings and equipment. Money in: $14.4 million local (mostly property tax), $21.8 million state, $3.8 million federal. Long-term debt: $10.7 million.
Spent $17.7 million — $15.2 million to run schools, about $13,909 per student, plus $2.1 million on buildings and equipment. Money in: $9.7 million local (mostly property tax), $7.3 million state, $1.6 million federal. Long-term debt: $1.9 million.
Spent $16.5 million — $15.1 million to run schools, about $14,345 per student, plus $1 million on buildings and equipment. Money in: $13.5 million local (mostly property tax), $6.1 million state, $793,000 federal. Long-term debt: $5 million.
Spent $15 million — $9.6 million to run schools, about $15,490 per student, plus $4.6 million on buildings and equipment. Money in: $4 million local (mostly property tax), $7.1 million state, $3 million federal. Long-term debt: $4.4 million.
Spent $5.1 million — $4.4 million to run schools, about $15,935 per student, plus $394,000 on buildings and equipment. Money in: $1.3 million local (mostly property tax), $3.6 million state, $695,000 federal. Long-term debt: $886,000.
And 1 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 Rock Island County about $45.4 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Very High; social vulnerability: Relatively High.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
272 bridges in Rock Island County: 125 in good condition, 134 fair, and 13 poor (4.8%). “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.
| IL 5 WB (J DEERE R over FAI 74 · built 1970 | 38,900 vehicles a day |
| 27TH ST - MOLINE over ROCK RIVER SIDE RD · built 1938 | 11,400 vehicles a day |
| 27TH ST.-MOLINE over STREAM · built 1937 | 10,050 vehicles a day |
| EAST 10TH AVE. over MILL CREEK · built 1985 | 7,750 vehicles a day |
| CH 16 over CASE CREEK · built 1983 | 4,450 vehicles a day |
| 39TH AVE over DRAINAGE DITCH · built 1972 | 1,600 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $44.1 million of work in Rock Island County in fiscal 2025, about $305 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 Rock Island 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 Island County built: brayden.ozark@gmail.com.
More of Illinois: the state government and every county in Illinois.
Nearby counties: Scott County, IA (12 mi) · Mercer County (20 mi) · Henry County (24 mi) · Muscatine County, IA (28 mi) · Clinton County, IA (30 mi) · Cedar County, IA (36 mi).