Mercer County, Illinois

Mercer County
Location within the U.S. state of Illinois
Illinois's location within the U.S.
Coordinates: 41°12′N 90°44′W / 41.2°N 90.74°W / 41.2; -90.74
Country United States
State Illinois
FoundedJanuary 13, 1825
Named afterHugh Mercer
SeatAledo
Largest cityAledo
Area
  Total
569 sq mi (1,470 km2)
  Land561 sq mi (1,450 km2)
  Water7.5 sq mi (19 km2)  1.3%
Population
 (2020)
  Total
15,699
  Estimate 
(2023)
15,487
  Density28/sq mi (11/km2)
Time zoneUTC−6 (Central)
  Summer (DST)UTC−5 (CDT)
Congressional districts15th, 17th
Websitewww.mercercountyil.org

Mercer County is a county in Illinois. According to the 2020 census, it had a population of 15,699. Its county seat is Aledo. Mercer County is included in the Davenport-Moline-Rock Island, IA-IL Metropolitan Statistical Area.