5,182,617 people (2024 Census estimate, −1.6% since 2020)
945 square miles of land · 5,485 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.
163 active community water systems list Cook County in the area they serve, reporting 5,222,867 people served in all (a system that crosses county lines counts its whole population).
| CHICAGO surface water · local government · IL0316000 | 2,721,308 served |
| CICERO buys surface water · local government · IL0310510 | 83,000 served |
| SCHAUMBURG buys surface water · local government · IL0314890 | 75,750 served |
| EVANSTON surface water · local government · IL0310810 | 74,486 served |
| ARLINGTON HEIGHTS buys surface water · local government · IL0314030 | 73,320 served |
| PALATINE buys surface water · local government · IL0312340 | 70,875 served |
| SKOKIE buys surface water · local government · IL0312880 | 66,422 served |
| DES PLAINES buys surface water · local government · IL0310630 | 60,675 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 4,788 people were held in Cook County's jail, in Vera's latest figure (2024), or 142 per 100,000 residents ages 15–64. In 2019 it was about 5,766.
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.
143 school districts have their office in Cook County. School taxes are usually the largest part of a property tax bill.
Spent $8.8 billion — $7.4 billion to run schools, about $22,916 per student, plus $762 million on buildings and equipment. Money in: $4.2 billion local (mostly property tax), $3 billion state, $1.5 billion federal. Long-term debt: $8.8 billion.
Spent $330.7 million — $306.8 million to run schools, about $20,497 per student, plus $21.1 million on buildings and equipment. Money in: $200.5 million local (mostly property tax), $105.7 million state, $21.8 million federal.
Spent $355.2 million — $324.8 million to run schools, about $26,471 per student, plus $23.2 million on buildings and equipment. Money in: $248.9 million local (mostly property tax), $95 million state, $13.6 million federal.
Spent $368.5 million — $324 million to run schools, about $26,880 per student, plus $34.6 million on buildings and equipment. Money in: $268.4 million local (mostly property tax), $103.4 million state, $13.1 million federal. Long-term debt: $26 million.
Spent $250 million — $218.4 million to run schools, about $19,671 per student, plus $27.7 million on buildings and equipment. Money in: $147 million local (mostly property tax), $73 million state, $14.4 million federal. Long-term debt: $39.6 million.
Spent $235.5 million — $206.2 million to run schools, about $23,390 per student, plus $25 million on buildings and equipment. Money in: $34.6 million local (mostly property tax), $187.4 million state, $43.3 million federal. Long-term debt: $55.6 million.
Spent $271.3 million — $201.2 million to run schools, about $24,613 per student, plus $63.5 million on buildings and equipment. Money in: $158.6 million local (mostly property tax), $62.5 million state, $8.1 million federal. Long-term debt: $128.5 million.
Spent $174.3 million — $153 million to run schools, about $18,807 per student, plus $17.1 million on buildings and equipment. Money in: $57 million local (mostly property tax), $136.2 million state, $17.6 million federal. Long-term debt: $80.5 million.
And 135 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: Very High compared with other U.S. counties. FEMA estimates natural hazards cost Cook County about $2.4 billion a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively High; social vulnerability: Relatively High.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
1,722 bridges in Cook County: 472 in good condition, 1,004 fair, and 246 poor (14.3%). “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.
| I- 90 94 RYAN ELEV over CANAL TO STEWART STS · built 1962 | 245,500 vehicles a day |
| I- 94 BISHOP FORD over RR - IHB & CSXT · built 1949 | 178,600 vehicles a day |
| I- 94 BISHOP FORD over GREENWOOD AVE · built 1947 | 152,900 vehicles a day |
| I- 94 BISHOP FORD over LITTLE CAL RIVER · built 1947 | 152,900 vehicles a day |
| IL 53 NB over KIRCHOFF RD · built 1963 | 123,700 vehicles a day |
| IL 53 SB over KIRCHOFF RD · built 1963 | 123,700 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $4.1 billion of work in Cook County in fiscal 2025, about $783 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 Cook 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 Cook County built: brayden.ozark@gmail.com.
More of Illinois: the state government and every county in Illinois.
Nearby counties: Lake County (22 mi) · DuPage County (23 mi) · Lake County, IN (32 mi) · Will County (35 mi) · Porter County, IN (40 mi) · Kane County (40 mi).