File:Jefferson_County_Courthouse_in_Mount_Vernon.jpg · Wikimedia Commons · See Wikimedia Commons
Jefferson County
Sign in to saveAlso known as Jefferson County, Illinois, Jefferson County, IL
county in Illinois, United States
Key facts
- Country
- United States
- State
- Illinois
- Named after
- Thomas Jefferson
- Seat
- Mount Vernon
- Largest city
- Mount Vernon
- Total
- 584 sq mi (1,510 km )
- Land
- 571 sq mi (1,480 km )
- Water
- 13 sq mi (34 km ) 2.2%
- Estimate 2025
- 36,147
- Density
- 65.0/sq mi (25.1/km )
- Time zone
- UTC−6 ( Central )
- Summer dst
- UTC−5 ( CDT )
- Congressional district
- 12th
- Website
- www .jeffersoncountyillinois .com
via Wikipedia infobox
Wikidata facts
- Population
- 37113
- Area
- 1512
- Official website
- jeffersoncounty.illinois.gov
- Image
- Jefferson County Courthouse in Mount Vernon.jpg
- Households
- 14792
Show 5 more facts
- Commons category
- Jefferson County, Illinois
- inception
- 1819-00-00
- water as percent of area
- 2.2
- native label
- Jefferson County
- per capita income
- 26742
Sources (9)
via Wikidata · CC0
~9 min read
Article
Jefferson County is a county located in the southern part of the U.S. state of Illinois. According to the 2020 census, it has a population of 37,113. The county seat is Mount Vernon. Jefferson County contains the Mount Vernon, Illinois micropolitan area. It is located in the southern portion known locally as "Little Egypt". The western border of the county adjoins the Greater St. Louis consolidated metropolitan statistical area, the Metro-East region, and the St. Louis commuter region and market and viewing area.
History