Illinois County Boundaries, 1790-Present
This is a wonderful series of maps - you can practically see the state being settled.
And this is a link to the Illinois GenWeb county links page (a clickable map) -
the counties vary in how much information they have online, but it is always worth a visit to see what they've got.
Adams formed 13 Jan 1825 from Pike
Transcription available for 1850 and 1880
Alexander formed 1819 from Johnson
Bond formed 4 Jan 1817 from Madison; Fayette, Pick, Montgomery and Sangamon 1821, Clinton 1824 formed from it.
Transcription available for 1820, 1830, 1850, 1860
Boone formed 4 March 1837 from Winnebago.
Transcription available for 1870
Brown formed 1 Feb 1839 from Schuyler
Transcription available for 1850, 1930
Bureau formed 28 Feb 1837 from Putnam
Calhoun formed 10 Jan 1825 from Pike
Carroll formed 22 Feb 1839 from Jo Daviess
Transcription available for 1900, 1910, 1920, 1930
Cass formed 3 March 1837 from Morgan
Champaign formed 20 Feb 1833 from Vermillion
Transcription available for 1850
Christian Dane County was formed 15 Feb 1839 and was renamed Christian 1 Feb 1840
Clark formed 22 March 1819 from Crawford; Pike and Fayette 1821, Edgar 1823, Coles 1830, Ford 1859 fromed from it.
Transcription available for 1820, 1850
Clay formed 23 Dec 1824 from Lawrence, Wayne and Fayette; Jasper 1831 and Richland 1841 formed from it.
Clinton formed 27 Dec 1824 from Washington, Bond and Fayette.
Transcription available for 1830, 1840, 1870, 1880, 1900, 1910, 1920
Coles formed 25 Dec 1830 from Clark and Edgar; Cumberland 1843, Douglass 1859 formed from it.
Transcription available for 1900
Cook formed 15 Jan 1831 from Putnam; McHenry and Will 1836 and DuPage 1839 formed from it.
Transcription available for 1860
Crawford formed 31 Dec 1816 from Edwards; Clark 1819, Effingham and Lawrence 1821, Jasper 1831 formed from it.
Transcription available for 1820, 1850
Cumberland formed 2 March 1843 from Coles.
Dane formed 15 Feb 1839 from Sangamon; renamed Christian in 1840.
DeKalb formed 4 March 1837 from Kane.
DeWitt formed 1 March 1839 from McLean and Macon; Piatt formed from it in 1841.
Transcription available for 1860
Douglas formed 8 Feb 1859 from Coles.
DuPage formed 9 Feb 1839 from Cook
Edgar formed 3 Jan 1823 from Clark County; Vermillion 1826 and Coles 1830 formed from it.
Transcription available for 1900
Edwards formed 28 Nov 1814 from Madison and Gallatin Counties; Crawford 1816, Wayne 1819, Lawrence 1821, Wabash 1827, and Jefferson 1839 formed from it.
Effingham formed 15 Feb 1831 from Fayette and Crawford.
Fayette formed 14 Feb 1821 from Bond, Jefferson, Wayne, Clark; Clay and Clinton 1824, Shelby and Tazewell 1827, Effingham 1831, Marion 1833 formed from it.
Ford formed 17 Feb 1859 from Clark
Franklin formed 2 Jan 1818 from White and Gallatin Counties; Williamson 1839 formed from it.
Transcription available for 1820, 1930
Fulton County formed 28 Jan 1823 from Pike County; Henry, Knox, Peoria, Putnam and Schuyler formed from it in 1825.
Transcription available for 1870, 1930
Gallatin formed 14 Sept 1812 from Randolph; Edwards 1814, White 1815, Pope 1816, Franklin 1818 and Saline formed from it.
Transcription available for 1820, 1830, 1840, 1850
Greene formed 20 Jan 1820 from Madison; Jersey (1819 - sic) and Macoupin (1829) formed from it.
Transcription available for 1830, 1840, 1850
Grundy formed 17 Feb 1841 from LaSalle
Transcription available for 1850
Hamilton formed 6 Feb 1821 from White
Transcription available for 1830, 1840, 1850
Hancock formed 13 Jan 1825 from Pike
Hardin formed 2 March 1839 from Pope
Henderson formed 20 Jan 1841 from Warren
Henry formed 13 Jan 1825 from Fulton; Jo Daviess 1827, Whiteside 1836 formed from it.
Iroquois formed 26 Feb 1823 from Vermillion - but it was not formally organized until 1834; Will 1836, Kankakee 1853 formed from it.
Jackson formed 10 Jan 1816 from Randolph and Johnson Counties; Perry 1841 formed from it.
Transcription available for 1820
Jasper formed 15 Feb 1841 from Crawford and Clay.
Jefferson formed 28 Feb 1839 from Edwards and White; Fayette 1821 (sic) and Marion 1833 (sic) formed from it.
Transcription available for 1820
Jersey formed 26 March 1819 from Greene
Jo Daviess formed 27 Feb 1827 from Mercer, Henry and Putnam counties; Rock Island 1831, Ogle, Whiteside and Winnebago 1836, Carroll and Stephenson 1837 formed from it.
Transcription available for 1860
Johnson formed 1812 from Randolph; Alexander 1819, Jackson and Pope 1816, Union 1818, Massac and Pulaski 1843 formed from it.
Kane formed 1836 from La Salle; De Kalb 1837 and Kendall 1841 formed from it.
Kankakee formed 11 Feb 1853 from Iroquois and Will.
Kendall formed 19 Feb 1841 from LaSalle and Kane.
Knox formed 13 Jan 1825 from Fulton; Stark formed from it in 1839.
Lake formed 1 March 1839 from McHenry.
LaSalle formed 15 Jan 1831 from Putnam and Vermillion; Kane1836, Livingston 1837, Grundy and Kendall 1841 formed from it.
Transcription available for 1850
Lawrence formed 16 Jan 1821 from Crawford and Edwards; Clay 1824 and Richmond 1841 formed from it.
Transcription available for 1830, 1920
Lee formed 27 Feb 1839 from Ogle.
Livingston formed 27 Feb 1837 from LaSalle and McLean
Logan formed 15 Feb 1839 from Sangamon and Tazewell Counties.
Transcription available for 1860
Macon formed 1829 from Shelby; DeWitt 1839, Pratt 1841, and Moultrie 1843 formed from it.
Macoupin formed 17 Jan 1829 from Madison and Greene Counties.
Madison formed 14 Sep 1812 from StClair; Edwards 1814, Bond 1817, Green, Montgomery, Pike and Sangamon 1821, and Macoupin 1829 formed from it.
Transcription available for 1820
Marion formed 24 Jan 1833 from Fayette and Jefferson.
Marshall formed 19 Jan 1839 from Putnam.
Marshall County has an especially good website devoted to it, hosted/owned by Nancy Piper - Piper's Pages. It seems to be connected with Genealogy Trails instead of GenWeb, but it is WONDERFUL.
Mason formed 20 Jan 1841 from Tazewell County.
Massac formed 8 Feb 1842 from Pope and Johnson Counties.
McDonough formed 25 Jan 1826 from Schuyler.
Transcription available for 1850, 1880
McHenry formed 16 Jan 1836 from Cook; Lake 1839 formed from it.
McLean formed 25 Dec 1830 from Tazewell; LIvingston 1837, DeWitt 1839 and Woodford 1841 formed from it.
Menard County formed 15 Feb 1839 from Sangamon County.
Mercer formed 13 Jan 1825 from Pike; Jo Daviess 1827 formed from it.
Monroe formed 6 Jan 1816 from Randolph and St. Clair.
Transcription available for 1820
Montgomery formed 12 Feb 1821 from Bond and Madison.
Morgan formed 1823 from Sangamon; Cass 1837 and Scott 1839 formed from it.
Transcription available for 1850
Moultrie formed 16 Feb 1843 from Shelby and Macon Counties.
Ogle formed 16 Jan 1836 from Jo Daviess; Lee formed from it in 1839
Transcription available for 1840, 1850, 1860
Peoria formed 13 Jan 1825 from Fulton
Transcription available for 1830, 1840, 1850, 1860, 1870
Perry formed 29 Jan 1841 from Randolph and Jackson Counties.
Transcription available for 1830, 1840, 1850, 1860, 1870
Piatt formed 20 Jan 1841 from DeWitt and Macon Counties.
Pike formed 31 Jan 1821 from Madison, Bond, Clark counties; Fulton 1823, Adams, Calhoun, Hancock, Mercer, Schuyler and Warren 1825 formed from it.
Transcription available for 1830, 1870
Pope formed 19 Jan 1816 from Johnson and Gallatin; Hardin 1839 and Massac 1843 formed from it.
Transcription available for 1820, 1850
Pulaski formed 3 March 1843 from Johnson County.
Putnam formed 13 Jan 1825 from Fulton; Jo Daviess 1827, LaSalle and Cook 1831, Bureau 1837, Marshall and Stark 1839 formed from it.
Transcription available for 1920
Randolph formed 5 Oct 1795 from St. Clair; Gallatin and Johnson 1812, Monroe and Jackson 1816, Perry 1841 formed from it.
In 1801, William Henry Harrison then Governor of Illinois, made St Clair and Randolph part of Indiana Territory; in 1803 he readjusted the boundaries. In 1805, Nathaniel Pope, acting territorial governor, put both counties in Indiana Territory.
Richland County formed 24 Feb 1841 from Clay and Lawrence Counties.
Rock Island formed 9 Feb 1831 from Jo Daviess
St Clair County formed 27 Apr 1790 from the Northwest Territory; Randolph 1795, Madison 1812, Monroe 1816, and Washington 1818 formed from it.
In 1801, William Henry Harrison then Governor of Illinois, made St Clair and Randolph part of Indiana Territory; in 1803 he readjusted the boundaries. In 1805, Nathaniel Pope, acting territorial governor, put both counties in Indiana Territory.
Transcription available for 1820
Saline formed 25 Feb 1847 from Gallatin.
Transcription available for 1850
Sangamon County formed 30 Jan 1821 from Bond and Madison; Morgan 1823, Christian, Logan, Menard and Dane 1839 formed from it.
Transcription available for 1830, 1850
Schuyler formed 1823 from Pike and Fulton; McDonough 1826 and Brown 1839 formed from it.
Transcription available for 1850
Scott formed 1839 from Morgan.
Transcription available for 1850
Shelby formed 13 Jan 1825 from Fayette; Macon 1829, Moultrie 1843 formed from it.
Transcription available for 1860, 1880
Stark formed 2 March 1839 from Knox and Putnam.
Transcription available for 1850
Stephenson formed 4 March 1837 from Winnebago and Jo Daviess
Tazewell formed 1827 from Fayette and Sangamon; McLean 1830, Logan 1839, Mason and Woodford 1841 formed from it.
Transcription available for 1850
Union formed 2 Jan 1818 from Johnson.
Transcription available for 1820
Vermillion formed 18 Jan 1826 from Edgar County; Iroquois 1823, LaSalle 1831, Champaign 1833 formed from it. (Spelling of Vermillion varies, sometimes one L, sometimes two)
Transcription available for 1860
Wabash formed 27 Dec 1827 from Edwards.
Transcription available for 1860
Warren formed 1825 from Pike; Henderson formed from it in 1841.
Washington formed 2 Jan 1818 from St. Clair; Clinton 1824 formed from it.
Transcription available for 1820, 1850
Wayne formed 1819 from Edwards; Fayette 1821 and Clay 1823 formed from it.
Transcription available for 1820, 1850
White formed 9 Dec 1815 from Gallatin; Franklin 1819, Hamilton 1821, Jefferson 1839 formed from it.
Transcription available for 1820, 1850
Whiteside formed 16 Jan 1836 from Jo Daviess and Henry
Bothwell land deals in Whiteside county (our Jeremiah was a player)
Will formed 12 Jan 1836 from Cook and Iroquois; Kankakee f 1853 formed from it.
Williamson formed 28 Feb 1839 from Franklin County.
Winnebago formed 16 Jan 1836 from Jo Daviess; Stephenson and Boone 1837 formed from it.
Woodford formed 1841 from Tazewell and McLean.
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Page last updated 28 July 2006