Illinois County Maps
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Illinois has 102 counties, a population of more than 13 million people, about 1,396 zip codes and 664 public school districts. Those counties vary widely in population, school enrollment, zip code coverage and local boundary structure. Cook County has the largest population in the state, while Hardin County has the smallest. Browse the map, population, zip codes, school districts, subdivisions and county list sections below to explore further. Or, simply start typing in the box below to go directly to that county.
Interactive Illinois County Map
This Illinois county map preview highlights population-by-county context, ZIP code coverage, school districts, and local boundary structure. Full statewide and county-level data packages are available when you need complete downloadable datasets. Click or tap any county to view its maps, trends and data.
Start with a free preview, or go straight to the full Illinois dataset .
Illinois Population By County
Illinois's population was over 13 million in 2020, down 18,124 (0.14%) residents from 2010. Cook County had the largest population in the state with more than 5 million people. DuPage and Lake Counties also stand out as major population centers. Hardin County was the least populated area in Illinois with only 3,649 residents. The table below compares Illinois county populations and recent population trends.
The Most Populated Counties In Illinois
| County | Population | Trend (2010-2020) |
|---|---|---|
| Cook County | 5,275,541 | ▴ 1.56% |
| DuPage County | 932,877 | ▴ 1.74% |
| Lake County | 714,342 | ▴ 1.55% |
| Will County | 696,355 | ▴ 2.77% |
| Kane County | 516,522 | ▴ 0.24% |
| Download all county population data | ||
County populations reflect the latest state serving context (2020).
Illinois County Map With ZIP Codes
Illinois has about 1,396 zip codes statewide. Cook County contains the most zip codes, with 167. County-level zip code maps give a faster and clearer way to understand local coverage as zip boundaries can span county and municipal lines. The maps below highlight a few Illinois counties.
Illinois School Districts By County
Illinois has 664 public school districts with 1,942,567 students enrolled as of 2024. Sangamon County has the highest district count in the state. DuPage County has the largest total school enrollment. Cook County posted the largest recent enrollment gain. The table below compares county level school district totals and recent enrollment trends across the state.
Largest School Districts in Illinois
| County | Districts | Enrollment | Trend |
|---|---|---|---|
| Sangamon County | 16 | 30,507 | ▾ 0.42% |
| Kane County | 13 | 129,717 | ▾ 0.33% |
| Montgomery County | 13 | 11,950 | ▾ 0.31% |
| Madison County | 12 | 37,592 | ▾ 0.67% |
| McLean County | 12 | 27,147 | ▾ 0.50% |
| Download all school district data | |||
School district enrollment and trend values reflect the most recent state-level context (2024).
Illinois County Map With Subdivisions
Illinois has about 1,695 local subdivisions statewide. These boundaries add another layer of detail within counties and help show how local subdivision lines fit inside county boundaries. The previews below highlight a few Illinois counties with subdivision map coverage.
Get the Full Illinois Data Package
The sections above provide a preview of Illinois county maps and county-level data. The full package includes complete statewide coverage with ready-to-use files for mapping, planning, and analysis.
Everything is organized to save hours of data collection, cleanup, and integration work.
- County map exports and boundary coverage for every county in Illinois
- Statewide GIS layers for ZIP codes, subdivisions, school districts, roads, water, and political boundaries
- Population, demographics, school, housing, and trend context aligned across counties
- Database files, map-ready exports, and documentation designed for faster research workflows
Includes GIS layers, maps, demographics, analytics, database files and planning tools.