History and Facts of Illinois Counties

IL State Facts

Territory: Mar 1, 1809
Statehood: Dec 3, 1818
Counties: 102
Borders: IN, KY, MO, IA and WI

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Today’s Illinois counties did not always exist in the present form. They went through many different changes in the space of a few short years. Illinois Counties were first formed while part of the Mississippi Territory, and after that the Illinois Territory.

Table of Contents hide

1 Illinois Territorial Counties

2 Illinois Counties Today

3 Fun Facts about Illinois Counties

3.1 Counties by Name

3.2 Counties by Year

3.3 County Size Facts

3.4 County Population Facts

3.5 Illinois City Facts

4 Boundary Changes of Illinois Counties from 1790-1869

5 List of Illinois Counties

6 List of Old Former / Extinct Illinois Counties

6.1 Dane County, Illinois

6.2 Hignland County, Illinois

6.3 Marquette County, Illinois

Illinois Territorial Counties

The Illinois Territory existed from March 1, 1809, until December 3, 1818. There were originally 15 Illinois counties when it gained statehood in 1818.

The State of Illinois entered the union as the 21st state on December 3, 1818.

Illinois Counties Today

Today, Illinois is divided into 102 counties. States bordering Illinois are Indiana, Kentucky, Missouri, Iowa and Wisconsin.

Fun Facts about Illinois Counties

Counties by Name

Most Illinois counties were named after

early American leaders from the American Revolutionary War, Battle of Tippecanoe and the War of 1812.
natural features
counties in other states
early Illinois leaders
2 counties are named for Native American tribes
1 bears the name of a plant used as a food source by Native Americans

Counties by Year

St. Clair County was an original County created on June 20, 1790.
Douglas County was the last county created on March 21, 1859.

County Size Facts

McLean County (1,184 sq mi) is the largest county in Illinois.
Putnam County (160 sq mi) is the smallest county in Illinois.

County Population Facts

Hardin County (4,836) is the least populated county in Illinois.
Cook County (5,194,675) is the most populated county in Illinois.

Illinois City Facts

Illinois’s 10 largest cities (2010 est.) are:

Chicago (2,695,598) is in Cook and DuPage Counties
Aurora (197,899) is in Kane, Will and DuPage Counties
Rockford (152,871) is in Winnebago County
Joliet (147,433) is in Will and Kendall Counties
Naperville (141,853) is in Will and DuPage Counties
Springfield (116,250) is in Sangamon County
Peoria (115,007) is in Peoria County
Elgin (108,188) is in Cook and Kane Counties
Waukegan (89,078) is in Lake County
Cicero (83,891) is in Cook County

Boundary Changes of Illinois Counties from 1790-1869

This Interactive Map of Illinois Counties show the historical boundaries, names, organization, and attachments of every county, extinct county and unsuccessful county proposal from 1790 to 1869.

List of Illinois Counties

County	Created	Created From	Named For	County Seat	Notes
Adams County	13 Jan 1825	Pike County	John Quincy Adams (1767–1848), sixth President of the United States	Quincy
Alexander County	04 Mar 1819	Union County	William M. Alexander, settler and state representative in the Illinois General Assembly	Cairo
Bond County	04 Jan 1817	Crawford County, Edwards County, and Madison County	Shadrach Bond (1773–1832), first Governor of Illinois	Greenville
Boone County	04 Mar 1837	Winnebago County	Daniel Boone (1734–1820), trailblazer of the Wilderness Road in Kentucky	Belvidere
Brown County	01 Feb 1839	Schuyler County	Jacob Brown (1775–1828), successful War of 1812 army officer responsible for Great Lakes defenses	Mount Sterling
Bureau County	28 Feb 1837	Putnam County	Pierre de Bureo, Frenchman, North American fur trader	Princeton
Calhoun County	10 Jan 1825	Pike County	John C. Calhoun (1782–1850), South Carolina senator and seventh Vice President of the United States	Hardin
Carroll County	22 Feb 1839	Jo Daviess	Charles Carroll of Carrollton (1737–1832), signed the Declaration of Independence on behalf of Maryland	Mount Carroll
Cass County	03 Mar 1837	Morgan County	Lewis Cass (1782–1866), second governor of Michigan Territory, fourteenth United States Secretary of War	Virginia
Champaign County	20 Feb 1833	Vermilion County	Champaign County, Ohio, which took its name from the French for “open level country”	Urbana
Christian County	01 Feb 1840	Crawford County	George Rogers Clark (1752–1818), highest-ranking officer in the Northwest Territory during the American Revolution	Carlyle
Clinton County	22 Mar 1819	Wayne, Lawrence, Fayette, and Crawford County	Henry Clay (1777–1852), Kentucky legislator who negotiated the Missouri Compromise	Marshall
Clark County	23 Dec 1824	Sangamon County	Christian County, Kentucky, which was itself named after Colonel William Christian	Taylorville
Clay County	27 Dec 1824	Washington, Bond, and Fayette County	DeWitt Clinton (1769–1828), Governor of New York, responsible for the construction of the Erie Canal	Louisville
Coles County	25 Dec 1830	Clark and Edgar County	Edward Coles (1786–1868), second Governor of Illinois, responsible for the abolition of slavery in Illinois	Charleston
Cook County	15 Jan 1831	Putnam County	Daniel Pope Cook (1794–1827), politician and first Attorney General of Illinois	Chicago
Crawford County	31 Dec 1816	Edwards County	William H. Crawford (1772–1834), ninth United States Secretary of War, seventh Secretary of the Treasury	Robinson
Cumberland County	02 Mar 1843	Coles County	Disputed: Cumberland Road, which entered the county; Cumberland, Maryland; or Cumberland River in Kentucky	Toledo
De Kalb County	04 Mar 1837	Macon and McLean County	DeWitt Clinton (1769–1828), Governor of New York, responsible for the construction of the Erie Canal	Tuscola
DeWitt County	01 Mar 1839	Kane County	Johann de Kalb (1721–1780), German soldier in the Continental Army who fought alongside Gilbert du Motier, marquis de Lafayette	Sycamore
Douglas County	21 Mar 1859	Coles County	Stephen A. Douglas (1813–61), prominent Illinois Democrat who engaged in debates with Abraham Lincoln	Clinton
DuPage County	09 Feb 1839	Cook County	DuPage River	Wheaton
Edgar County	03 Jan 1823	Clark County	John Edgar (c. 1750–1832), Illinois delegate to the Northwest Territory legislature; at the time, wealthiest man in Illinois	Paris
Edwards County	28 Nov 1814	Gallatin County and Madison County	Ninian Edwards (1775–1833), third Governor of the State of Illinois and only governor of the Illinois Territory	Albion
Effingham County	15 Feb 1831	Fayette and Crawford County	Thomas Howard, 3rd Earl of Effingham, military officer who resigned from the British Army to avoid fighting the American colonies	Effingham
Fayette County	14 Feb 1821	Bond, Wayne, Clark, Jefferson, and Crawford County	Gilbert du Motier, marquis de Lafayette (1757–1834), French military officer who was a key factor in the American and French Revolutions.	Vandalia
Ford County	17 Feb 1859	Vermilion County	Thomas Ford (1800–50), eighth Governor of Illinois; served during the Illinois Mormon War	Paxton
Franklin County	02 Jan 1818	White County and Gallatin County	Benjamin Franklin (1706–90), prolific writer, inventor, and politician; key factor in the American Revolution	Benton
Fulton County	28 Jan 1823	Pike County	Robert Fulton (1765–1815), inventor of the steamboat	Lewistown
Gallatin County	14 Sep 1812	Randolph County	Albert Gallatin (1761–1849), fourth and longest-serving United States Secretary of the Treasury	Shawneetown
Grundy County	20 Jan 1821	Madison County	Nathanael Greene (1742–86), major general in the Continental Army	Carrollton
Greene County	17 Feb 1841	LaSalle County	Felix Grundy (1777–1840), Tennessean senator who served as the thirteenth United States Attorney General	Morris
Hamilton County	08 Feb 1821	White County	Alexander Hamilton (1755–1804), first United States Secretary of the Treasury	McLeansboro
Hancock County	13 Jan 1825	Adams County	John Hancock (1737–93), first governor of the Massachusetts colony and president of the Second Continental Congress	Carthage
Hardin County	02 Mar 1839	Pope County	Hardin County, Kentucky, which was itself named after John Hardin	Elizabethtown
Henry County	20 Jan 1841	Warren County	Henderson County, Kentucky, which was itself named after Richard Henderson	Oquawka
Henderson County	13 Jan 1825	Fulton County	Patrick Henry (1736-99), American Revolutionary War figure; first and sixth Governor of Virginia	Cambridge
Iroquois County	26 Feb 1823	Vermilion County	Iroquois Native Americans	Watseka
Jackson County	10 Jan 1816	Randolph County and Johnson County	Andrew Jackson (1767–1845), seventh President of the United States, United States Senator from Tennessee, and general in the War of 1812	Murphysboro
Jasper County	15 Feb 1831	Clay and Crawford County	Sgt. William Jasper (c. 1750-79), American Revolutionary War soldier popularized by Parson Weems	Newton
Jefferson County	28 Feb 1839	Edwards and White County	Thomas Jefferson (1743–1826), third President of the United States, second Vice President of the United States, Governor of Virginia, and one of the foremost Founding Fathers of the United States	Galena
Jersey County	26 Mar 1819	Greene County	State of New Jersey, from which many early settlers hailed	Mount Vernon
Jo Daviess County	27 Feb 1827	Henry, Mercer, and Putnam County	Joseph Hamilton Daveiss (1774–1811), commander of the Indiana Dragoons at the Battle of Tippecanoe	Jerseyville
Johnson County	14 Sep 1812	Randolph County	Richard Mentor Johnson (abt. 1780-1850), ninth Vice President of the United States and United States Senator from Kentucky	Vienna
Kane County	16 Jan 1836	LaSalle County	Elias Kane (1794–1835), United States Senator from Illinois	Geneva
Kankakee County	11 Feb 1853	Iroquois and Will Counties	Kankakee River	Kankakee
Kendall County	19 Feb 1841	LaSalle and Kane Counties	Amos Kendall (1789–1869), United States Postmaster General under Presidents Andrew Jacksonand Martin Van Buren	Yorkville
Knox County	13 Jan 1825	Fulton County	Gen. Henry Knox (1750–1806), American Revolutionary War general and first United States Secretary of War	Galesburg
Lake County	01 Mar 1839	McHenry County	Lake Michigan	Waukegan
La Salle County	15 Jan 1831	Putnam and Tazewell Counties	Sieur de la Salle (1643-87), French explorer of the Great Lakes	Lawrenceville
Lawrence County	16 Jan 1821	Crawford and Edwards Counties	Capt. James Lawrence (1781–1813), commander of the USS Chesapeake in the War of 1812. Famous for his command “Don’t give up the ship!”	Dixon
Lee County	27 Feb 1839	Ogle County	“Light Horse” Henry Lee III (1756–1818), American Revolutionary War officer and ninth Governor of Virginia	Pontiac
Livingston County	27 Feb 1837	LaSalle and McLean Counties	Edward Livingston (1764–1836), prominent jurist, Congressman from New York and Louisiana, and U.S. Secretary of State from 1831-33	Lincoln
Logan County	15 Feb 1839	Sangamon and Tazewell Counties	John Logan, country doctor and early settler, and the father of John A. Logan	Lincoln
Macon County	19 Jan 1829	Fayette and Jefferson Counties	Francis Marion (c. 1732-95), general in the American Revolutionary War known as “The Swamp Fox”	Bloomington
Macoupin County	17 Jan 1829	Cook and LaSalle Counties	Major William McHenry (c. 1771 – 1835), officer in during several campaigns against Native Americans and member of the Illinois legislature	Sullivan
Madison County	14 Sep 1812	Sangamon County	John Logan, country doctor and early settler, and the father of John A. Logan	Ottawa
Marion County	24 Jan 1833	Tazewell County	John McLean (1791–1830), United States Representative and United States Senator from Illinois (the latter from 1824-25 and 1829-30)	Carlinville
Marshall County	19 Jan 1839	Randolph County and St. Clair County	James Monroe (1758–1831), seventh United States Secretary of State, eighth United States Secretary of War, Governor of Virginia, and fifth President of the United States	Metropolis
Mason County	20 Jan 1841	Bond and Madison County	Gen. Richard Montgomery (1738-75), brigadier-general in the Continental Army who led the unsuccessful invasion of Canada	Lacon
Massac County	08 Feb 1843	Schuyler County	Hugh Mercer (1726-77), British officer in the Seven Years’ War and general in the Continental Army during the American Revolutionary War	Waterloo
McDonough County	25 Jan 1826	Shelby County	Nathaniel Macon (1758–1837), sixth Speaker of the United States House of Representatives and United States Senator from North Carolina	Edwardsville
McHenry County	16 Jan 1836	Greene County	Native American word macoupin, meaning “American lotus”	Macomb
McLean County	25 Dec 1830	St. Clair County and Randolph County	James Madison (1751–1836), fourth President of the United States and principal author of the Constitution of the United States	Woodstock
Menard County	15 Feb 1839	Putnam County	John Marshall (1755–1835), fourth and longest-serving Chief Justice of the United States, wrote opinion in Marbury v. Madison establishing the principle of judicial review	Decatur
Mercer County	13 Jan 1825	Tazewell and Menard County	Named after Mason County, Kentucky, itself named after George Mason	Petersburg
Monroe County	06 Jan 1816	Sangamon County	Pierre Menard (1766–1844), prominent early settler and first Lieutenant Governor of Illinois	Salem
Montgomery County	12 Feb 1821	Sangamon County	Gen. Daniel Morgan (1736–1802), successful tactician in the American Revolutionary War and later United States Representative from Virginia	Havana
Morgan County	31 Jan 1823	Pope and Johnson County	Fort Massac, a colonial-era fort on the Ohio River	Aledo
Moultrie County	16 Feb 1843	Schuyler County	Commodore Thomas Macdonough (1783–1825), commander of American naval forces at the Battle of Plattsburgh	Jacksonville
Ogle County	16 Jan 1836	Shelby and Macon County	Gen. William Moultrie (1730–1805), American Revolutionary War general and Governor of South Carolina	Hillsboro
Peoria County	13 Jan 1825	Jo Daviess	Joseph Ogle (1737–1821), early settler in southwest Illinois, who helped found the first Methodistchurch in Illinois	Oregon
Perry County	29 Jan 1841	Fulton County	The Peoria Native American tribe	Peoria
Piatt County	20 Jan 1841	Randolph and Jackson County	Commodore Oliver Hazard Perry (1785–1819), American naval officer who led the victorious American forces at the Battle of Lake Erie	Pinckneyville
Pike County	31 Jan 1821	DeWitt and Macon County	John Piatt, the patriarch of a prominent settler family in the early history of the county	Monticello
Pope County	10 Jan 1816	Madison, Bond, and Clark County	Zebulon Pike (1779–1813), early explorer of the American Southwest, namesake of Pikes Peak	Pittsfield
Pulaski County	03 Mar 1843	Gallatin and Johnson County	Nathaniel Pope (1784–1850), early Delegate from Illinois Territory to Congress and judge on the United States District Court for the District of Illinois	Golconda
Putnam County	13 Jan 1825	Alexander and Johnson County	Gen. Casimir Pulaski (1745-79), Polish American general of cavalry in the American Revolutionary War	Mound City
Randolph County	05 Oct 1795	Fulton County	Gen. Israel Putnam (1718-90), commander of American forces at the Battle of Bunker Hill	Hennepin
Rock Island County	24 Feb 1841	Clay and Lawrence County	Richland County, Ohio, itself named for its rich soil	Olney
Richland County	09 Feb 1831	St. Clair County	Edmund Randolph (1753–1813), first Attorney General of the United States, and briefly United States Secretary of State	Chester
St. Clair County	27 Apr 1790	Madison and Bond County	Sangamon River	Springfield
Saline County	25 Feb 1847	Jo Daviess County	Rock Island	Rock Island
Sangamon County	30 Jan 1821	Gallatin County	Salt springs within the county	Harrisburg
Schuyler County	13 Jan 1825	Pike and Fulton County	Gen. Philip Schuyler (1733–1804), American Revolutionary War general and United States Senator from New York	Belleville
Scott County	16 Feb 1839	Morgan County	Scott County, Kentucky, itself named after Charles Scott	Rushville
Shelby County	23 Jan 1827	Fayette County	Isaac Shelby (1750–1826), soldier in the American Revolutionary War and War of 1812; first and fifth Governor of Kentucky	Winchester
Stark County	02 Mar 1839	original two counties	Arthur St. Clair (1737–1818), major general in the American Revolutionary War and first Governor of the Northwest Territory	Shelbyville
Stephenson County	04 Mar 1837	Knox and Putnam County	Gen. John Stark (1728–1822), general in the American Revolutionary War, called the “Hero of Bennington”	Toulon
Tazewell County	31 Jan 1827	Jo Daviess and Winnebago County	Benjamin Stephenson (1769–1822), representative of Illinois Territory in the United States Congress from 1814 to 1816	Freeport
Union County	02 Jan 1818	Sangamon County	Littleton Waller Tazewell (1774–1860), United States Senator from (and later governor of) Virginia	Pekin
Vermilion County	18 Jan 1826	Johnson County	The federal union of the states	Jonesboro
Wabash County	27 Dec 1827	Edwards County	The Wabash River	Mount Carmel
Warren County	13 Jan 1825	Schuyler County	Joseph Warren (1741-75), played a role in American Patriot movements, a prominent early fatality in the American Revolutionary War	Monmouth
Washington County	02 Jan 1818	St. Clair County	George Washington (1732-99), commander-in-chief of American forces in the American Revolutionary War and first President of the United States	Nashville
Wayne County	26 Mar 1819	Edwards County	Gen. “Mad” Anthony Wayne (1745-96), major general in the United States Army in the American Revolutionary War and the Northwest Indian War	Fairfield
White County	09 Dec 1815	Gallatin County	Isaac White (1776–1811), resident of Illinois who enlisted in the Indiana militia and was killed at the Battle of Tippecanoe	Carmi
Whiteside County	16 Jan 1836	Jo Daviess and Henry Counties	Samuel Whiteside (1783–1868), state legislator and militia leader	Morrison
Will County	12 Jan 1836	Cook and Iroquois Counties	Conrad Will (1779–1835), physician, local businessman and longtime member of the state legislature	Joliet
Williamson County	28 Feb 1839	Franklin County	Hugh Williamson (1735–1819), delegate from North Carolina to the Philadelphia Convention	Marion
Winnebago County	16 Jan 1836	Jo Daviess County	Winnebago Native Americans	Rockford
Woodford County	27 Feb 1841	Tazewell and McLean Counties	Gen. William Woodford (1734-80), brigadier general in the American Revolutionary War who died while a British prisoner	Eureka
Old Dane County (Extinct)	15 Feb 1839	Sangamon County			On February 1, 1840 it was renamed Christian County 1 February 1840
Old Hignland County (Extinct)	27 Feb 1847	renaming Marquette County			On December 31, 1848 it was merged with Adams County
Old Knox County (Extinct)	20 Jun 1790	the Northwest Territory from non-county area; included parts of present Illinois, Indiana, Michigan, Ohio, and Wisconsin.			On March 1, 1809 it became extinct with the formation of the Illinois Territory in 1809
Old Marquette County (Extinct)	11 Feb 1843	Adams County			February 27, 1847
Old Wayne County (Extinct)	15 Aug 1796	Northwest Territory from HAMILTON (Ohio), KNOX (Ind.), and non-county area in the Northwest Territory			On July 4, 1800 it was eliminated from present Illinois when Indiana Territory was created from the Northwest Territory.
Old Wayne County (Extinct)	01 Mar 1803	Knox and St. Clair Counties			On June 30, 1805 it was eliminated when Michigan Territory was created from Indiana Territory.

List of Old Former / Extinct Illinois Counties

Illinois contains some counties that no longer exist because they were discontinued, renamed or merged with another county. These are important for genealogy research purposes.

The below counties formerly within the area of the State of Illinois no longer exist:

Dane County, Illinois

Created on February 15, 1839 from Montgomery aand Sangamon Counties. Dane County was renamed to Christian County on February 1, 1840.

Hignland County, Illinois

Created on February 27, 1847 from Marquette County. Highland County was merged into Adams County on December 31, 1848.

Marquette County, Illinois

Created on February 1, 1843 from Adams County. Marquette County was renamed to Hignland County on February 27, 1847.