ILLINOIS STATE ARCHIVES

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Mercer County

Established
January 13, 1825 (Laws, 1825, p. 93)
County organization was completed in 1835.

Origin of the name of the county
Named for Hugh Mercer, a General of the Revolution, killed at the battle of Princeton.

Present area, or parts of it, formerly included in
1831–1835 — Attached to Warren (Laws, 1831, p. 68.)
1826–1831 — Attached to Peoria (Laws, 1826, p. 76.)
1825–1826 — Attached to Schuyler (Laws, 1825, p. 95.)
1821–1825 — Pike
1812–1821 — Madison
1795–1812 — St. Clair

County Seats
1835–1837 — New Boston – Temporary designation.
1837–1847 — Millersburg
1847–1857 — Keithsburg
1857–  — Aledo

History of county governing board
1835–1849 — County Commissioners’ Court
1849–1854 — County Court
1854–  — County Board of Supervisors

Township Government
Adopted — November 8, 1853

Township Names
Abington
Duncan
Eliza
Greene
Keithsburg
Mercer — Name changed from Centre (date unknown, before 1921).
Millersburg
New Boston
North Henderson — Name changed from Liberty (date unknown, before 1921).
Ohio Grove — Name changed from Ohio (date unknown, after 1921).
Perryton
Preemption — Name changed from Fairfield (date unknown, before 1921).
Richland Grove
Rivoli — Name changed from North Pope (date unknown, before 1921).
Suez — Name changed from Palmyra (date unknown, before 1921).

Township Map

Pertinent Databases
Federal Township Plats of Illinois
Illinois Public Domain Land Tract Sales Database
Illinois Statewide Death Index, 1916–1950
Illinois Statewide Marriage Index
Local Governmental Records Database
Mercer County Almshouse Register Index (1859–1948)
Name Index to Illinois Local Governments