Marion County
Also known as Marion County, Illinois, Marion County, IL
county in Illinois, United States
Key facts
- Country
- United States
- State
- Illinois
- Named after
- Francis Marion
- Seat
- Salem
- Largest city
- Centralia
- Total
- 576 sq mi (1,490 km )
- Land
- 572 sq mi (1,480 km )
- Water
- 3.7 sq mi (9.6 km ) 0.6%
- Estimate 2025
- 36,382
- Density
- 66.0/sq mi (25.5/km )
- Time zone
- UTC−6 ( Central )
- Summer dst
- UTC−5 ( CDT )
- Congressional district
- 15th
~5 min read
Article
Marion County is a county located in the U.S. state of Illinois. According to the 2020 census, it had a population of 37,729. Its county seat is Salem. Marion County comprises the Centralia, IL Micropolitan Statistical Area, which is included in the St. Louis-St. Charles-Farmington, MO-IL Combined Statistical Area.
History