Key facts
- Country
- United States
- State
- Illinois
- Named after
- William M. Alexander
- Seat
- Cairo
- Largest city
- Cairo
- Total
- 253 sq mi (660 km )
- Land
- 236 sq mi (610 km )
- Water
- 17 sq mi (44 km ) 6.8%
- Estimate 2025
- 4,570
- Density
- 22.2/sq mi (8.57/km )
- Time zone
- UTC−6 ( Central )
- Summer dst
- UTC−5 ( CDT )
- Congressional district
- 12th
Article
Alexander County is the southernmost county in the U.S. state of Illinois. In the 2020 census, the population was 5,240. Its county seat is Cairo and its western boundary is formed by the Mississippi River.
Alexander County is part of the Cape Girardeau–Jackson metropolitan area which is made up of jurisdictions on both sides of the Mississippi River.