Mercer County is a county located in the state of Illinois. According to the 2010 census, it had a
population of 16,434. Mercer County was created
on January 13, 1825. The county seat is Aledo.
The county is named for General Hugh Mercer
(1726-1777), British officer in the Seven Years' War and general in the
Continental Army during the American Revolutionary War.
Mercer County is included in the Davenport-Moline-Rock Island, IA-IL Metropolitan Statistical Area.
The county is named for General Hugh Mercer, killed at the Battle of Princeton during the American Revolution.
County QuickFacts: CensusBureau Quick Facts
Mercer County was created on January 13, 1825 (Laws, 1825, p. 93) and was formed from unorganized land (Pike County).
County organization was completed in 1835. Present area, or parts of it, formerly included in: Attached to Warren County
[Laws, 1831, p. 68.] (1831-1835), Attached to Peoria County [Laws, 1826, p. 76.] (1826-1831), Attached to Schuyler
County [Laws, 1825, p. 95.] (1825-1826), Pike County (1821-1825), Madison County (1812-1821) and St. Clair County
(1795-1812).
The County was named for Hugh Mercer, a General of the Revolution, killed at the battle of Princeton. The County Seat is
Aledo . Prior County Seats was New Boston- Temporary designation (1835-1837), Millersburg (1837-1847), Keithsburg
(1847-1857) and Aledo (1857-Present).
As reported by the Census Bureau, the county has a total area of 569 square miles (1,473 km2), of which, 561 square miles (1,453 km2) of it is land and 8 square miles (20 km2) of it (1.38%) is water.
Mercer county is located in northwest Illinois.
Bordering counties are as follows: