Alexander County, Illinois

Alexander County
Location within the U.S. state of Illinois
Illinois's location within the U.S.
Coordinates: 37°11′N 89°20′W / 37.19°N 89.34°W / 37.19; -89.34
Country United States
State Illinois
Founded1819
Named afterWilliam M. Alexander
SeatCairo
Largest cityCairo
Area
  Total
253 sq mi (660 km2)
  Land236 sq mi (610 km2)
  Water17 sq mi (40 km2)  6.8%
Population
 (2020)
  Total
5,240
  Estimate 
(2024)
4,594
  Density21/sq mi (8.0/km2)
Time zoneUTC−6 (Central)
  Summer (DST)UTC−5 (CDT)
Congressional district12th
Websitewww.alexandercountyil.com

Alexander County is the southernmost county in the U.S. state of Illinois. As of 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.