Jefferson County, Illinois
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... Wikipedia
- Founded: 1819
- Named for: Thomas Jefferson
- Seat: Mount Vernon
- Largest city: Mount Vernon
- Total: 584 sq mi (1,512.55 km²)
- Land: 571 sq mi (1,478.88 km²)
- Water: 13 sq mi (33.67 km²), 2.2
- Density: auto/sq mi (/km²)
- Time zone: Central: UTC-6-5
- Data source: DuckDuckGo