ILLINOIS STATE ARCHIVES

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Cook County

Established
January 15, 1831 (Laws, 1831, p. 54)

Origin of the name of the county
Named for Daniel P. Cook, a pioneer lawyer, first Attorney General of the State of Illinois and Representative in Congress from 1819 to 1827.

Present area, or parts of it, formerly included in
1825–1831 — Putnam
1823–1825 — Fulton
1821–1823 — Pike
1819–1821 — Clark
1816–1819 — Crawford
1815–1816 — Edwards
1812–1815 — Madison
1801–1812 — St. Clair
1795–1801 — Knox, Northwest Territory

County Seats
1831–   — Chicago

History of county governing board
1831–1850 — County Commissioners’ Court
1850–  — County Board of Supervisors

Documented Record Losses
October 9, 1871 — Fire. Total record loss (1831–1871).

Township Government
Adopted — November 6, 1849

Township Names
Barrington
Berwyn
Bloom
Bremen
Calumet — Formed as Hope on June 2, 1862; name changed on June 17, 1862.
Cicero — Formed on June 4, 1860.
Elk Grove
Evanston
Hanover
Lemont — Name changed from Palmyra in April, 1850.
Leyden — Name changed from Monroe in April, 1850.
Lyons
Maine
New Trier
Niles
Northfield
Norwood Park — Formed on February 3, 1873
Oak Park
Orland
Palatine
Palos — Name changed from Trenton in April, 1850.
Proviso — Name changed from Taylor in April, 1850.
Rich
River Forest
Riverside — Formed on September 24, 1870.
Schaumburg
Stickney — Formed from Lyons on May 3, 1901.
Thornton
Wheeling
Worth

Township Map

Pertinent Databases
Chicago City Council Proceedings Files Index (1833–1871)
Chicago Police Department Homicide Record (1870–1930)
Cook County Coroner's Inquest Record Index (1872–1911)
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
Name Index to Illinois Local Governments