Jefferson County, Illinois
Jefferson County, Illinois, has 36,147 residents (July 2025 estimate). Its county seat is Mount Vernon. It uses Central Time and covers 571 sq mi (1,479 km²) of land.
- Resident population, July 2025
- 36,147
- Land area
- 571 sq mi (1,479 km²)
- County seat or government
- Mount Vernon
- Time zone
- Central TimeUTC-06:00 in January; UTC-05:00 in July
- Median household income
- $63,118 ± $2,847
- Median home value
- $126,000 ± $6,496
- Median rent, with utilities
- $885 ± $31
- Homes lived in by their owners
- 71.7% ± 1.4 points
- County type
- County
- Metro or micro area
- Mount Vernon, IL micro areaCentral county
- Water area
- 12.6 sq mi (32.5 km²)
- State
- Illinois
- County code (FIPS)
- 17081
- Coordinates (central point)
- 38.300780, -88.924210
These coordinates mark a central point for the area, not a street address. Income, home value, rent and homes lived in by their owners: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates, ± margin at 90% confidence; checked on October 13, 2026.
Time zones in Jefferson County
| Time zone | Local time and UTC offset | Next clock change |
|---|---|---|
| Central TimeAmerica/Chicago | UTC-06:00 in January; UTC-05:00 in July. Enable JavaScript for the live clock. | Enable JavaScript for upcoming changes. |
Near a time-zone line, check where you are with the time-zone finder. Your phone’s setting can differ.
ZIP Code areas, largest first
- 6286422,779 people
- 6280119,827 people
- 628981,968 people
- 628461,798 people
- 628141,668 people
- 628081,602 people
- 628301,416 people
- 628101,188 people
- 628721,153 people
- 628161,133 people
- 628891,066 people
- 62893926 people
17 ZIP Code areas overlap Jefferson County. People counts are 2020–2024 estimates for each whole ZIP area. Mailing ZIPs can differ; check an address with USPS ZIP Code Lookup.
Official county information
We don’t have a website for this county yet. The US government’s local-office directory ↗ lists its offices. A geographic lookup cannot determine eligibility, tax liability or a court obligation.
Townships in Jefferson County, largest first
- Mount Vernon Township12,335 people
- Shiloh Township6,520 people
- Dodds Township2,700 people
- Spring Garden Township2,574 people
- Field Township1,730 people
- Webber Township1,636 people
- Rome Township1,576 people
- Pendleton Township1,454 people
- McClellan Township1,047 people
- Grand Prairie Township988 people
- Casner Township907 people
- Bald Hill Township805 people
All 16
- Farrington Township783 people
- Elk Prairie Township569 people
- Blissville Township546 people
- Moores Prairie Township380 people
People counts are American Community Survey 2020–2024 5-year estimates. All townships in Illinois, by county
School districts in Jefferson County, largest first
- Mount Vernon Township High School District 20128,299 people
- Centralia High School District 20019,500 people
- Salem Community High School District 60014,607 people
- Benton Consolidated High School District 10312,750 people
- Centralia School District 13512,655 people
- Mount Vernon School District 8012,389 people
- Nashville Community High School District 998,431 people
- Hamilton County Community Unit School District 107,368 people
- Sesser-Valier Community Unit School District 1964,166 people
- Spring Garden Community Consolidated School District 1783,748 people
- Wayne City Community Unit School District 1003,704 people
- Field Community Consolidated School District 32,993 people
All 33
- Rome Community Consolidated School District 22,542 people
- Ewing Northern Community Consolidated District 1152,370 people
- Summersville School District 792,303 people
- Opdyke-Belle Rive Community Consolidated School District 52,106 people
- Waltonville Community Unit School District 12,054 people
- Woodlawn Unit District 2091,896 people
- Ashley Community Consolidated School District 151,672 people
- Bluford Unit School District 3181,586 people
- Bethel School District 821,117 people
- Grand Prairie Community Consolidated School District 6947 people
- Kell Consolidated School District 2895 people
- Farrington Community Consolidated School District 99833 people
- Bluford Unit School District 318 (9-12) in Farrington815 people
- McClellan Community Consolidated School District 12692 people
- Woodlawn Unit District 209 (9-12) in Grand Prairie558 people
- Woodlawn Unit District 209 (KG-8) in Mount Vernon529 people
- Woodlawn Unit District 209 (9-12) in Rome489 people
- Bluford Unit School District 318 (KG-8) in Mount Vernon346 people
- Woodlawn Unit District 209 (9-12) in Ashley125 people
- Woodlawn Unit District 209 (KG-8) in Nashville25 people
- Bluford Unit School District 318 (9-12) in Opdyke-Belle Rive0 people
Districts with land in the county; a district can cross county lines. People counts are American Community Survey 2020–2024 5-year estimates. A district boundary doesn’t decide which school a student attends.
Cities, towns and communities, largest first
These areas overlap the mapped boundary; an overlap does not mean that every address belongs to both.
- Mount Vernon, Illinois (city)14,090 people
- Centralia, Illinois (city)11,856 people
- Ina, Illinois (village)1,560 people
- Woodlawn, Illinois (village)632 people
- Dix, Illinois (village)568 people
- Bluford, Illinois (village)483 people
- Bonnie, Illinois (village)461 people
- Belle Rive, Illinois (village)382 people
- Waltonville, Illinois (village)294 people
- Opdyke, Illinois (CDP)246 people
- Nason, Illinois (city)203 people
Bordering areas, nearest first
Distances are straight lines between map points.
- Franklin County, Illinois21 mi south
- Marion County, Illinois24 mi north
- Hamilton County, Illinois26 mi southeast
- Washington County, Illinois27 mi west
- Wayne County, Illinois28 mi east
- Perry County, Illinois28 mi southwest
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