Marion County GIS Maps
Marion County, Illinois, has 37,729 residents and covers 572.5 square miles. The population declined 4.3% between the 2010 and 2020 census. More residents left than arrived over that decade. The FIPS code for Marion County is 17121.
Centralia is the county's largest population center. Marion County also includes 10 zip codes, 4 public school districts and 35 municipalities. Those boundaries help explain why population, schools, and housing can look different from one part of the county to another. The map below shows how those county lines, zip codes, and school districts fit together, and the sections that follow use that same geography to show population, demographics, school enrollment and housing patterns in more detail.
Maps, GIS layers and sample data. Paid packages add full layers, analytics and database files.
Marion County Trends
- Population
- 37,729▾
- Median Home Value
- $100,100▴
- K-12 Enrollment
- 1,481▾
County analytics dashboards with historical trends & projections included in package downloads.
Free starter access previews county maps, lightweight GIS, and sample data. Paid packages unlock full GIS layers, analytics, and database files.
Marion County Maps
The maps below show a few of the county map styles included in our downloads. County packages include map exports in JPEG, PNG, SVG, PDF and GeoTIFF formats plus more than 20 GIS layers for mapping, research and analysis. Available layers include zip codes, area codes, subdivisions, school districts, political boundaries, roads, water features, points of interest and more.
County packages also include historical county demographics, business intelligence, analytical dashboards, AI-ready prompts, markdown files and related reference data. Everything is organized to save hours of manual work collecting current data, cleaning it and joining it together. That makes it easier to move faster on analytics, due diligence, business planning and location research. Paid packages are built for commercial use, but some package contents include source-specific attribution or notice guidance. Review Licensing & Data Source Notices.
Marion County Population
Marion County had 37,729 residents in 2020. That was 4.3% lower than in 2010. Marion County had 3,962 fewer people in 2020 than it did in 2000, which points to a long-term population decline. The county is fairly spread out, with about 66 people per square mile. Some of the county's most populated postal areas include Centralia, Salem and Sandoval.
Population Trend in Marion County IL
Marion County Population per 2000, 2010 and 2020 census counts with a baseline 2030 projection.
Marion County Zip Codes
Marion County has 10 zip codes. Some of the county's most populated zip codes include Centralia (62801), Salem (62881) and Sandoval (62882). Centralia is the largest zip by population, with about 20,502 residents or 54% of the county total. Together, the three largest zips account for about 90% of all county residents based on 2020 population estimates.
Most Populated Zip Codes in Marion County IL
| ZIP | Area | Population | Trend |
|---|---|---|---|
| 62801 | Centralia | 20,502 | ▾ -8.5% |
| 62881 | Salem | 11,053 | ▾ -2.9% |
| 62882 | Sandoval | 2,215 | ▾ -5% |
| 62849 | Iuka | 2,181 | ▾ -1.1% |
| 62870 | Odin | 1,890 | ▾ -9.1% |
| Download all zip code data | |||
Marion County Zip Code populations and trends per most recent census data.
Marion County Demographics
Marion County has a median age of 41.3, which makes the county a little older than Illinois overall. About 23.6% of residents are under 18, while 19.8% are 65 or older. That gives the county a fairly even mix of younger families and older adults. The largest age group is 25 to 44 at about 29.6% of the population, which points to a solid working-age base. About 17.3% of adults have a bachelor's degree or higher, above the statewide figure of 37.2%. The county is mostly White by population, though Hispanic, Asian, Black and multiracial residents are also part of the local mix.
Key Demographics for Marion County IL
Median Age
41.3
Under 18
23.6%
Age 65+
19.8%
Bachelor's+
17.3%
Marion County School Districts
Marion County is served by 4 public school districts with 1,481 students enrolled in 2024. The largest districts on the county map are South Central Community Unit 401, Sandoval Community Unit 501 and Odin Public 722. Those three districts account for about 86% of public school enrollment in the map area. Total enrollment has stayed fairly steady in recent years, but it is slightly lower than it was in 2017.
Largest School Districts by Enrollment in Marion County IL
| District | Enrollment | Share | Trend |
|---|---|---|---|
| South Central Community Unit School District 401 | 592 | 40% | ▾ -5.9% |
| Sandoval Community Unit School District 501 | 429 | 29% | ▾ -0.5% |
| Odin Public School District 722 | 259 | 17.5% | ▴ 12.6% |
| Patoka Community Unit School District 100 | 201 | 13.6% | ▾ -10.7% |
| Download all school district data | |||
Marion County school district enrollment and trends per most recent NCES reporting data.
Marion County Housing & Real Estate
Marion County has a median home value of $100,100 and a median gross rent of $771. About 74% of occupied homes in the county are owner-occupied, so the local housing market leans heavily toward ownership. Home values run below the Illinois median, while rents come in below the state average. In March 2026, the median listing price was $158,950 and homes spent about 89 days on the market.
Marion County Housing Mix
Marion County housing mix: owner, renter and vacant units.
Marion County Housing Trends
Marion County median home value and rent trend (last 5 years).
Businesses in Marion County, IL
Marion County has 1,569 business listings across 390 categories. The largest categories in Marion County business listings are Churches & Religious Organizations (86, 5.5%), Insurance Agencies (35, 2.2%), and Auto Repair (33, 2.1%). The full Marion County business listings dataset includes names, categories, addresses and contact details where available. Marion County packages also include U.S. Census County Business Patterns data with establishment counts, employment and payroll by industry sector.
Top Business Categories in Marion County, IL
| Category | Businesses | Share |
|---|---|---|
| Churches & Religious Organizations | 86 | 5.5% |
| Insurance Agencies | 35 | 2.2% |
| Auto Repair | 33 | 2.1% |
| Elementary School | 24 | 1.5% |
| Beauty Salons | 23 | 1.5% |
| Public And Government Association | 22 | 1.4% |
| Bars & Nightlife | 21 | 1.3% |
| Banks & Credit Unions | 20 | 1.3% |
| Gas Stations | 19 | 1.2% |
| Baptist Church | 17 | 1.1% |
Marion County Business Listings
| Business | Category | City |
|---|---|---|
| Rockin' ASE Ranch | Accommodation | Centralia |
| Leymone Hardcastle & Co | Accountant | Salem |
| Forbes Lake | Active Life | Salem |
| TruL Photography | Advertising Agency | Centralia |
| Marion County Farm Bureau | Agricultural Cooperatives | Salem |
| The Equity at Alma | Agricultural Service | Alma |
| Centralia Municipal Airport | Airport | Centralia |
| Lifestar Ambulance | Ambulance And Ems Services | Centralia |
| Downtown Lounge | American Restaurants | Centralia |
| City of Salem, Illinois Animal Control | Animal Shelters | Kell |
| Download Marion County business listings | ||
Marion County business listings sourced from Overture Maps. Includes locations with a high level of confidence.
Marion County Basemaps
Marion County map and data packages include a set of useful basemaps to help you get started quickly. These include a custom light grey canvas, USGS topo, imagery and other reference layers that make it easier to build clear, meaningful county maps using the included GIS layers, your own data or both. Pre-rendered map tiles for the light grey basemap are included so you can use them offline or host them on your own CDN.
Get the Full Marion County Data Package
This page shows a preview of what's included in the Marion County data package. The full package gives you a ready-to-use county data system with GIS layers, historical data, maps, database files and planning tools that save hours of manual data gathering, cleanup and joins. Everything is organized to help you skip data wrangling and start analysis faster.
- 20+ GIS layers for zip codes, school districts, roads, water, boundaries and more
- Historical county demographics, housing, income and trend data
- ZIP code population files and school district enrollment history
- Database files, markdowns, AI-ready prompts and documentation
- Map exports in PNG, JPEG, PDF, SVG and GeoTIFF formats
- Offline-ready data explorer, map and analytics tools
Paid packages support commercial use, client work, and derived outputs. Some package contents may include source-specific attribution or provider notices. See Licensing & Data Source Notices.
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Nearby Counties
Browse county data pages for the counties that border Marion County. These nearby pages include the same mix of county maps, demographic summaries, school district context, housing trends and package links.