List of counties in Illinois

There are 102 counties in the U.S. state of Illinois. The largest of these by population is Cook County, home to Chicago and the second-most populous county in the United States, while the smallest is Hardin County. The largest by area is McLean County while the smallest is Putnam County. Illinois's FIPS state code is 17 and its postal abbreviation is IL.

Counties of Illinois
LocationState of Illinois
Populations4,836 (Hardin) – 5,194,675 (Cook)
Areas160 square miles (410 km2) (Putnam) – 1,184 square miles (3,070 km2) (McLean)

What is now Illinois was claimed as part of Illinois County, Virginia, between 1778 and 1782. Modern-day county formation dates to 1790 when the area was part of the Northwest Territory; two counties—St. Clair and Knox—were created at that time. Knox would later become a county in Indiana and is unrelated to the current Knox County in Illinois, while St. Clair would become the oldest county in Illinois. 15 counties had been created by the time Illinois achieved statehood in 1818. The last county, Ford County, was created in 1859. Cook County, established in 1831 and named for the early Illinois Attorney General Daniel Pope Cook, contained the absolute majority of the state's population in the first half of the 20th century and retains more than 40% of it as of the 2010 Census.

Most counties in Illinois were named after early American leaders, especially of the American Revolutionary War, as well as soldiers from the Battle of Tippecanoe and the War of 1812. Some are named after natural features or counties in other states. Some are named for early Illinois leaders. Two counties are named for Native American tribes, and one bears the name of a plant used as a food source by Native Americans. While it does have a Lincoln city, Illinois does not have a county named after its favorite son, Abraham Lincoln; it does, however, have a Douglas County (founded 1859) named after his political rival Stephen A. Douglas. It also has Calhoun County (founded 1825), named after John C. Calhoun, outspoken for his pro-slavery and pro-southern views in the years preceding the American Civil War. Several of the counties are named after Southerners, reflecting the fact that Illinois was for a short time part of Virginia, and settled in its early years by many Southerners. No counties are named after heroes of the Civil War, mainly because the counties were all named before that war. The state does have a Lee County (founded 1839) named after the family of Robert E. Lee, who at one time served in Illinois. Illinois also has two counties named after the same person, New York governor DeWitt Clinton (DeWitt County, and Clinton County).

Information on the FIPS county code, county seat, year of establishment, origin, etymology, population, area and map of each county is included in the table below.


Note: the links in the FIPS County Code column are to the United States Census Bureau page for that county.

FIPS code[1] County seat[2] Est.[2] Origin Etymology[3][4] Population[2] Area[2] Map
Adams County 001 Quincy 1825 Pike County John Quincy Adams (1767–1848), sixth President of the United States 65,691 855 sq mi
(2,214 km2)
Alexander County 003 Cairo 1819 Union County William M. Alexander, settler and state representative in the Illinois General Assembly 6,060 235 sq mi
(609 km2)
Bond County 005 Greenville 1817 Crawford County, Edwards County, and Madison County Shadrach Bond (1773–1832), first Governor of Illinois 16,630 380 sq mi
(984 km2)
Boone County 007 Belvidere 1837 Winnebago County Daniel Boone (1734–1820), trailblazer of the Wilderness Road in Kentucky 53,577 280 sq mi
(725 km2)
Brown County 009 Mount Sterling 1839 Schuyler County Jacob Brown (1775–1828), successful War of 1812 army officer responsible for Great Lakes defenses 6,556 305 sq mi
(790 km2)
Bureau County 011 Princeton 1837 Putnam County Pierre de Bureo, Frenchman, North American fur trader 32,993 869 sq mi
(2,251 km2)
Calhoun County 013 Hardin 1825 Pike County John C. Calhoun (1782–1850), South Carolina senator and seventh Vice President of the United States 4,802 253 sq mi
(655 km2)
Carroll County 015 Mount Carroll 1839 Jo Daviess Charles Carroll of Carrollton (1737–1832), signed the Declaration of Independence on behalf of Maryland 14,312 445 sq mi
(1,153 km2)
Cass County 017 Virginia 1837 Morgan County Lewis Cass (1782–1866), second governor of Michigan Territory, fourteenth United States Secretary of War 12,260 375 sq mi
(971 km2)
Champaign County 019 Urbana 1833 Vermilion County Champaign County, Ohio, which took its name from the French for "open level country" 209,983 996 sq mi
(2,580 km2)
Christian County 021 Taylorville 1839 Sangamon County Christian County, Kentucky, which was itself named after Colonel William Christian 32,661 709 sq mi
(1,836 km2)
Clark County 023 Marshall 1819 Crawford County George Rogers Clark (1752–1818), highest-ranking officer in the Northwest Territory during the American Revolution 15,596 501 sq mi
(1,298 km2)
Clay County 025 Louisville 1824 Wayne, Lawrence, Fayette, and Crawford County Henry Clay (1777–1852), Kentucky legislator who negotiated the Missouri Compromise 13,253 468 sq mi
(1,212 km2)
Clinton County 027 Carlyle 1824 Washington, Bond, and Fayette County DeWitt Clinton (1769–1828), Governor of New York, responsible for the construction of the Erie Canal 37,639 474 sq mi
(1,228 km2)
Coles County 029 Charleston 1830 Clark and Edgar County Edward Coles (1786–1868), second Governor of Illinois, responsible for the abolition of slavery in Illinois 50,885 508 sq mi
(1,316 km2)
Cook County 031 Chicago 1831 Putnam County Daniel Pope Cook (1794–1827), politician and first Attorney General of Illinois 5,180,493 944 sq mi
(2,445 km2)
Crawford County 033 Robinson 1816 Edwards County William H. Crawford (1772–1834), ninth United States Secretary of War, seventh Secretary of the Treasury 18,807 443 sq mi
(1,147 km2)
Cumberland County 035 Toledo 1843 Coles County Disputed: Cumberland Road, which entered the county; Cumberland, Maryland; or Cumberland River in Kentucky 10,808 345 sq mi
(894 km2)
DeKalb County 037 Sycamore 1837 Kane County Johann de Kalb (1721–1780), German soldier in the Continental Army who fought alongside Gilbert du Motier, marquis de Lafayette 104,143 631 sq mi
(1,634 km2)
DeWitt County 039 Clinton 1839 Macon and McLean County DeWitt Clinton (1769–1828), Governor of New York, responsible for the construction of the Erie Canal 15,769 397 sq mi
(1,028 km2)
Douglas County 041 Tuscola 1859 Coles County Stephen A. Douglas (1813–1861), prominent Illinois Democrat who engaged in debates with Abraham Lincoln 19,479 416 sq mi
(1,077 km2)
DuPage County 043 Wheaton 1839 Cook County DuPage River 928,589 327 sq mi
(847 km2)
Edgar County 045 Paris 1823 Clark County John Edgar (c. 1750–1832), Illinois delegate to the Northwest Territory legislature; at the time, wealthiest man in Illinois 17,360 623 sq mi
(1,614 km2)
Edwards County 047 Albion 1814 Gallatin County and Madison County Ninian Edwards (1775–1833), third Governor of the State of Illinois and only governor of the Illinois Territory 6,392 222 sq mi
(575 km2)
Effingham County 049 Effingham 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 34,208 478 sq mi
(1,238 km2)
Fayette County 051 Vandalia 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. 21,416 716 sq mi
(1,854 km2)
Ford County 053 Paxton 1859 Vermilion County Thomas Ford (1800–1850), eighth Governor of Illinois; served during the Illinois Mormon War 13,264 485 sq mi
(1,256 km2)
Franklin County 055 Benton 1818 White County and Gallatin County Benjamin Franklin (1706–1790), prolific writer, inventor, and politician; key factor in the American Revolution 38,701 408 sq mi
(1,057 km2)
Fulton County 057 Lewistown 1823 Pike County Robert Fulton (1765–1815), inventor of the steamboat 34,844 865 sq mi
(2,240 km2)
Gallatin County 059 Shawneetown 1812 Randolph County Albert Gallatin (1761–1849), fourth and longest-serving United States Secretary of the Treasury 5,058 322 sq mi
(834 km2)
Greene County 061 Carrollton 1821 Madison County Nathanael Greene (1742–1786), major general in the Continental Army 13,044 543 sq mi
(1,406 km2)
Grundy County 063 Morris 1841 LaSalle County Felix Grundy (1777–1840), Tennessean senator who served as the thirteenth United States Attorney General 50,972 418 sq mi
(1,083 km2)
Hamilton County 065 McLeansboro 1821 White County Alexander Hamilton (1755–1804), first United States Secretary of the Treasury 8,163 434 sq mi
(1,124 km2)
Hancock County 067 Carthage 1825 Adams County John Hancock (1737–1793), first governor of the Massachusetts colony and president of the Second Continental Congress 17,844 793 sq mi
(2,054 km2)
Hardin County 069 Elizabethtown 1839 Pope County Hardin County, Kentucky, which was itself named after John Hardin 3,910 177 sq mi
(458 km2)
Henderson County 071 Oquawka 1841 Warren County Henderson County, Kentucky, which was itself named after Richard Henderson 6,709 378 sq mi
(979 km2)
Henry County 073 Cambridge 1825 Fulton County Patrick Henry (1736–1799), American Revolutionary War figure; first and sixth Governor of Virginia 49,090 822 sq mi
(2,129 km2)
Iroquois County 075 Watseka 1833 Vermilion County Iroquois Native Americans 27,604 1,117 sq mi
(2,893 km2)
Jackson County 077 Murphysboro 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 57,419 584 sq mi
(1,513 km2)
Jasper County 079 Newton 1831 Clay and Crawford County Sgt. William Jasper (c. 1750–1779), American Revolutionary War soldier popularized by Parson Weems 9,611 494 sq mi
(1,279 km2)
Jefferson County 081 Mount Vernon 1819 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 37,820 571 sq mi
(1,479 km2)
Jersey County 083 Jerseyville 1839 Greene County State of New Jersey, from which many early settlers hailed 21,847 369 sq mi
(956 km2)
Jo Daviess County 085 Galena 1827 Henry, Mercer, and Putnam County Joseph Hamilton Daveiss (1774–1811), commander of the Indiana Dragoons at the Battle of Tippecanoe 21,366 600 sq mi
(1,554 km2)
Johnson County 087 Vienna 1812 Randolph County Richard Mentor Johnson (c. 1780–1850), ninth Vice President of the United States and United States Senator from Kentucky 12,456 343 sq mi
(888 km2)
Kane County 089 Geneva 1836 LaSalle County Elias Kane (1794–1835), United States Senator from Illinois 534,216 519 sq mi
(1,344 km2)
Kankakee County 091 Kankakee 1853 Iroquois and Will County Kankakee River 110,024 676 sq mi
(1,751 km2)
Kendall County 093 Yorkville 1841 LaSalle and Kane County Amos Kendall (1789–1869), United States Postmaster General under Presidents Andrew Jackson and Martin Van Buren 127,915 320 sq mi
(829 km2)
Knox County 095 Galesburg 1825 Fulton County Gen. Henry Knox (1750–1806), American Revolutionary War general and first United States Secretary of War 50,112 716 sq mi
(1,854 km2)
Lake County 097 Waukegan 1839 McHenry County Lake Michigan 700,832 443 sq mi
(1,147 km2)
LaSalle County 099 Ottawa 1831 Putnam and Tazewell County Sieur de la Salle (1643–1687), French explorer of the Great Lakes 109,430 1,135 sq mi
(2,940 km2)
Lawrence County 101 Lawrenceville 1821 Crawford and Edwards County 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!" 15,765 372 sq mi
(963 km2)
Lee County 103 Dixon 1839 Ogle County "Light Horse" Henry Lee III (1756–1818), American Revolutionary War officer and ninth Governor of Virginia 34,223 724 sq mi
(1,875 km2)
Livingston County 105 Pontiac 1837 LaSalle and McLean County Edward Livingston (1764–1836), prominent jurist, Congressman from New York and Louisiana, and U.S. Secretary of State from 1831-33 35,761 1,043 sq mi
(2,701 km2)
Logan County 107 Lincoln 1839 Sangamon County John Logan, country doctor and early settler, and the father of John A. Logan 28,925 618 sq mi
(1,601 km2)
Macon County 115 Decatur 1829 Shelby County Nathaniel Macon (1758–1837), sixth Speaker of the United States House of Representatives and United States Senator from North Carolina 104,712 580 sq mi
(1,502 km2)
Macoupin County 117 Carlinville 1829 Greene County Native American word macoupin, meaning "American lotus" 45,313 862 sq mi
(2,233 km2)
Madison County 119 Edwardsville 1812 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 264,461 716 sq mi
(1,854 km2)
Marion County 121 Salem 1823 Fayette and Jefferson County Francis Marion (c. 1732–1795), general in the American Revolutionary War known as "The Swamp Fox" 37,620 572 sq mi
(1,481 km2)
Marshall County 123 Lacon 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 11,534 386 sq mi
(1,000 km2)
Mason County 125 Havana 1841 Tazewell and Menard County Named after Mason County, Kentucky, itself named after George Mason 13,565 539 sq mi
(1,396 km2)
Massac County 127 Metropolis 1843 Pope and Johnson County Fort Massac, a colonial-era fort on the Ohio River 14,080 237 sq mi
(614 km2)
McDonough County 109 Macomb 1826 Schuyler County Commodore Thomas Macdonough (1783–1825), commander of American naval forces at the Battle of Plattsburgh 29,955 589 sq mi
(1,526 km2)
McHenry County 111 Woodstock 1836 Cook and LaSalle County Major William McHenry (c. 1771–1835), officer during several campaigns against Native Americans and was a member of the Illinois legislature 308,570 603 sq mi
(1,562 km2)
McLean County 113 Bloomington 1830 Tazewell County John McLean (1791–1830), United States Representative and United States Senator from Illinois (the latter from 1824-25 and 1829-30) 172,828 1,183 sq mi
(3,064 km2)
Menard County 129 Petersburg 1839 Sangamon County Pierre Menard (1766–1844), prominent early settler and first Lieutenant Governor of Illinois 12,288 314 sq mi
(813 km2)
Mercer County 131 Aledo 1825 Schuyler County Hugh Mercer (1726–1777), British officer in the Seven Years' War and general in the Continental Army during the American Revolutionary War 15,601 561 sq mi
(1,453 km2)
Monroe County 133 Waterloo 1816 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 34,335 385 sq mi
(997 km2)
Montgomery County 135 Hillsboro 1821 Bond and Madison County Gen. Richard Montgomery (1738–1775), brigadier-general in the Continental Army who led the unsuccessful invasion of Canada 28,601 703 sq mi
(1,821 km2)
Morgan County 137 Jacksonville 1823 Sangamon County Gen. Daniel Morgan (1736–1802), successful tactician in the American Revolutionary War and later United States Representative from Virginia 33,976 568 sq mi
(1,471 km2)
Moultrie County 139 Sullivan 1843 Shelby and Macon County Gen. William Moultrie (1730–1805), American Revolutionary War general and Governor of South Carolina 14,717 335 sq mi
(868 km2)
Ogle County 141 Oregon 1836 Jo Daviess Joseph Ogle (1737–1821), early settler in southwest Illinois, who helped found the first Methodist church in Illinois 50,923 758 sq mi
(1,963 km2)
Peoria County 143 Peoria 1825 Fulton County The Peoria Native American tribe 180,621 618 sq mi
(1,601 km2)
Perry County 145 Pinckneyville 1827 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 21,174 441 sq mi
(1,142 km2)
Piatt County 147 Monticello 1841 DeWitt and Macon County James A. Piatt, the patriarch of a prominent settler family in the early history of the county 16,396 439 sq mi
(1,137 km2)
Pike County 149 Pittsfield 1821 Madison, Bond, and Clark County Zebulon Pike (1779–1813), early explorer of the American Southwest, namesake of Pikes Peak 15,611 831 sq mi
(2,152 km2)
Pope County 151 Golconda 1816 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 4,212 368 sq mi
(953 km2)
Pulaski County 153 Mound City 1843 Alexander and Johnson County Gen. Casimir Pulaski (1745–1779), Polish American general of cavalry in the American Revolutionary War 5,463 199 sq mi
(515 km2)
Putnam County 155 Hennepin 1825 Fulton County Gen. Israel Putnam (1718–1790), commander of American forces at the Battle of Bunker Hill 5,740 160 sq mi
(414 km2)
Randolph County 157 Chester 1795 St. Clair County Edmund Randolph (1753–1813), first Attorney General of the United States, and briefly United States Secretary of State 32,106 575 sq mi
(1,489 km2)
Richland County 159 Olney 1841 Clay and Lawrence County Richland County, Ohio, itself named for its rich soil 15,763 360 sq mi
(932 km2)
Rock Island County 161 Rock Island 1831 Jo Daviess County Rock Island 143,477 427 sq mi
(1,106 km2)
Saline County 165 Harrisburg 1847 Gallatin County Salt springs within the county 23,906 379 sq mi
(982 km2)
Sangamon County 167 Springfield 1821 Madison and Bond County Sangamon River 195,348 868 sq mi
(2,248 km2)
Schuyler County 169 Rushville 1825 Pike and Fulton County Gen. Philip Schuyler (1733–1804), American Revolutionary War general and United States Senator from New York 6,907 437 sq mi
(1,132 km2)
Scott County 171 Winchester 1839 Morgan County Scott County, Kentucky, itself named after Charles Scott 4,926 250 sq mi
(647 km2)
Shelby County 173 Shelbyville 1827 Fayette County Isaac Shelby (1750–1826), soldier in the American Revolutionary War and War of 1812; first and fifth Governor of Kentucky 21,741 758 sq mi
(1,963 km2)
St. Clair County 163 Belleville 1790 original two counties Arthur St. Clair (1737–1818), major general in the American Revolutionary War and first Governor of the Northwest Territory 261,059 657 sq mi
(1,702 km2)
Stark County 175 Toulon 1839 Knox and Putnam County Gen. John Stark (1728–1822), general in the American Revolutionary War, called the "Hero of Bennington" 5,427 288 sq mi
(746 km2)
Stephenson County 177 Freeport 1837 Jo Daviess and Winnebago County Benjamin Stephenson (1769–1822), representative of Illinois Territory in the United States Congress from 1814 to 1816 44,753 564 sq mi
(1,461 km2)
Tazewell County 179 Pekin 1827 Sangamon County Littleton Waller Tazewell (1774–1860), United States Senator from (and later governor of) Virginia 132,328 646 sq mi
(1,673 km2)
Union County 181 Jonesboro 1818 Johnson County The federal union of the states 16,841 413 sq mi
(1,070 km2)
Vermilion County 183 Danville 1826 Edgar County The Vermilion River 76,806 898 sq mi
(2,326 km2)
Wabash County 185 Mount Carmel 1824 Edwards County The Wabash River 11,549 223 sq mi
(578 km2)
Warren County 187 Monmouth 1825 Schuyler County Joseph Warren (1741–1775), played a role in American Patriot movements, a prominent early fatality in the American Revolutionary War 17,032 542 sq mi
(1,404 km2)
Washington County 189 Nashville 1818 St. Clair County George Washington (1732–1799), commander-in-chief of American forces in the American Revolutionary War and first President of the United States 13,995 562 sq mi
(1,456 km2)
Wayne County 191 Fairfield 1819 Edwards County Gen. "Mad" Anthony Wayne (1745–1796), major general in the United States Army in the American Revolutionary War and the Northwest Indian War 16,332 713 sq mi
(1,847 km2)
White County 193 Carmi 1815 Gallatin County Isaac White (1776–1811), resident of Illinois who enlisted in the Indiana militia and was killed at the Battle of Tippecanoe 13,665 494 sq mi
(1,279 km2)
Whiteside County 195 Morrison 1836 Jo Daviess and Henry County Samuel Whiteside (1783–1868), state legislator and militia leader 55,626 684 sq mi
(1,772 km2)
Will County 197 Joliet 1836 Cook and Iroquois County Conrad Will (1779–1835),[5] physician, local businessman and longtime member of the state legislature 692,310 835 sq mi
(2,163 km2)
Williamson County 199 Marion 1839 Franklin County Hugh Williamson (1735–1819), delegate from North Carolina to the Philadelphia Convention 67,056 420 sq mi
(1,088 km2)
Winnebago County 201 Rockford 1836 Jo Daviess Winnebago Native Americans 284,081 513 sq mi
(1,329 km2)
Woodford County 203 Eureka 1841 Tazewell and McLean County Gen. William Woodford (1734–1780), brigadier general in the American Revolutionary War who died while a British prisoner 38,463 527 sq mi
(1,365 km2)

Defunct countiesEdit

See alsoEdit


  1. ^ "U.S. Census Bureau 2019 FIPS Codes". Retrieved January 8, 2021.
  2. ^ a b c d "County Explorer". National Association of Counties. Retrieved January 8, 2021.
  3. ^ "Illinois County Biographies". Genealogy Genealogy Trails. 2000. Retrieved September 21, 2008.
  4. ^ "The Origin of Illinois County Names". Genealogy Genealogy Trails. 2000. Retrieved September 21, 2008.
  5. ^ Matile, Roger (June 22, 2006). "Reflections: Was Dr. Conrad Will really worth his salt?". Ledger-Sentinel. Retrieved October 11, 2011.


External linksEdit