NAME OF COUNTY DATE FORMED COUNTY SEAT
ST. CLAIR APR. 27, 1790 BELLEVILLE
RANDOLPH OCT. 5, 1795 CHESTER
GALLATIN SEPT. 14, 1812 SHAWNEETOWN
JOHNSON SEPT. 14, 1812 VIENNA
MADISON SEPT. 14, 1812 EDWARDSVILLE
EDWARDS NOV. 28, 1814 ALBION
WHITE DEC. 9, 1815 CARMI
JACKSON JAN. 10, 1816 MURPHYSBORO
MONROE JAN. 6, 1816 WATERLOO
POPE JAN. 10, 1816 GOLCONDA
CRAWFORD DEC. 31, 1816 ROBINSON
FRANKLIN JAN. 2, 1818 BENTON
UNION JAN. 2, 1818 JONESBORO
WASHINGTON JAN. 2, 1818 NASHVILLE
ALEXANDER MAR. 4, 1819 CAIRO
CLARK MAR. 22, 1819 MARSHALL
JEFFERSON MAR. 26, 1819 MT. VERNON
WAYNE MAR. 26, 1819 FAIRFIELD
LAWRENCE JAN. 16, 1821 LAWRENCEVILLE
GREENE JAN. 20, 1821 CARROLLTON
SANGAMON JAN. 30, 1821 SPRINGFIELD
PIKE JAN. 31, 1821 PITTSFIELD
HAMILTON FEB. 8, 1821 MCLEANSBORO
MONTGOMERY FEB. 12, 1821 HILLSBORO
FAYETTE FEB. 14, 1821 VANDALIA
EDGAR JAN. 3, 1823 PARIS
FULTON JAN. 28, 1823 LEWISTOWN
MARION JAN. 24, 1823 SALEM
MORGAN JAN. 31, 1823 JACKSONVILLE
CLAY DEC. 23, 1824 LOUISVILLE
WABASH DEC. 27, 1824 MOUNT CARMEL
CLINTON DEC. 27, 1824 CARLYLE
ADAMS JAN. 13, 1825 QUINCY
CALHOUN JAN. 10, 1825 HARDIN
ADAMS JAN. 13, 1825 QUINCY
HANCOCK JAN. 13, 1825 CARTHAGE
HENRY JAN. 13, 1825 CAMBRIDGE
MERCER JAN. 13, 1825 ALEDO
KNOX JAN. 13, 1825 GALESBURG
PEORIA JAN. 13, 1825 PEORIA
PUTNAM JAN. 13, 1825 HENNEPIN
SCHUYLER JAN. 13, 1825 RUSHVILLE
WARREN JAN. 13, 1825 MONMOUTH
MCDONOUGH JAN. 25, 1826 MACOMB
VERMILION JAN. 18, 1826 DANVILLE
SHELBY JAN. 23, 1827 SHELBYVILLE
PERRY JAN. 29, 1827 PINCKNEYVILLE
TAZEWELL JAN. 31, 1827 PEKIN
JODAVIESS FEB. 17, 1827 GALENA
MACOUPIN JAN. 17, 1829 CARLINVILLE
MACON JAN. 19, 1829 DECATUR
COLES DEC. 25, 1830 CHARLESTON
MCLEAN DEC. 25, 1830 BLOOMINGTON
COOK JAN. 15, 1831 CHICAGO
LASALLE JAN. 15, 1831 OTTAWA
EFFINGHAM FEB. 15, 1831 EFFINGHAM
JASPER FEB. 15, 1831 NEWTON
ROCK ISLAND FEB. 9, 1831 ROCK ISLAND
CHAMPAIGN FEB. 20, 1833 URBANA
IROQUOIS FEB. 26, 1833 WATSEKA
KANE JAN. 16, 1836 GENEVA
MCHENRY JAN. 16, 1836 WOODSTOCK
OGLE JAN. 16, 1836 OREGON
WHITESIDE JAN. 16, 1836 MORRISON
WILL JAN. 12, 1836 JOLIET
WINNEBAGO JAN. 16, 1836 ROCKFORD
BOONE MAR. 4, 1837 BELVIDERE
LIVINGSTON FEB. 27, 1837 PONTIAC
BUREAU FEB. 28, 1837 PRINCETON
CASS MAR. 3, 1837 VIRGINIA
DEKALB MAR. 4, 1837 SYCAMORE
STEPHENSON MAR. 4, 1837 FREEPORT
BROWN FEB. 1, 1839 MOUNT STERLING
DUPAGE FEB. 9, 1839 WHEATON
CHRISTIAN FEB. 15, 1839 TAYLORVILLE
LOGAN FEB. 15, 1839 LINCOLN
CARROLL FEB. 22, 1839 MOUNT CARROLL
LEE FEB. 27, 1839 DIXON
JERSEY FEB. 28, 1839 JERSEYVILLE
LAKE MAR. 1, 1839 WAUKEGAN
DEWITT MAR. 1, 1839 CLINTON
HARDIN MAR. 2, 1839 ELIZABETHTOWN
MARSHALL JAN. 19, 1839 LACON
MENARD FEB. 15, 1839 PETERSBURG
SCOTT FEB. 16, 1839 WINCHESTER
STARK MAR. 2, 1839 TOULON
WILLIAMSON FEB. 28, 1839 MARION
HENDERSON JAN. 20, 1841 OQUAWKA
MASON JAN. 20, 1841 HAVANA
PIATT JAN. 27, 1841 MONTICELLO
GRUNDY FEB. 17, 1841 MORRIS
KENDALL FEB. 19, 1841 YORKVILLE
RICHLAND FEB. 24, 1841 OLNEY
WOODFORD FEB. 27, 1841 EUREKA
MASSAC FEB. 8, 1843 METROPOLIS
MOULTRIE FEB. 16, 1843 SULLIVAN
CUMBERLAND MAR. 2, 1843 TOLEDO
PULASKI MAR. 3, 1843 MOUND CITY
SALINE FEB. 25, 1847 HARRISBURG
KANKAKEE FEB. 11, 1853 KANKAKEE
DOUGLAS FEB. 8, 1859 TUSCOLA
FORD FEB. 17, 1859 PAXTON