Illinois's County Tapestry
A comprehensive academic exploration of the 102 administrative divisions that shape the Prairie State, from their historical genesis to their unique naming legacies.
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County Overview
Administrative Landscape
The state of Illinois is comprised of 102 distinct counties, each serving as a fundamental administrative and geographical unit. These counties collectively form the intricate governmental structure of the state, managing local services and representing diverse communities across its expansive territory.
Population Extremes
Among these 102 counties, a significant disparity in population is observed. Cook County, home to the metropolis of Chicago, stands as the most populous, not only within Illinois but also as the second-most populous county in the entire United States. In stark contrast, Hardin County represents the least populous, highlighting the varied demographic profiles across the state.
Geographical Dimensions
Geographically, the counties of Illinois also present a wide range in size. McLean County holds the distinction of being the largest by land area, encompassing a substantial portion of the state's central plains. Conversely, Putnam County is the smallest in terms of land area, demonstrating the diverse scales at which these administrative divisions are organized. Illinois's Federal Information Processing Standard (FIPS) state code is 17, and its postal abbreviation is IL.
Historical Origins
Early Territorial Claims
The territory that now constitutes Illinois was initially claimed as part of Illinois County, Virginia, a designation that existed between 1778 and 1782. This early claim reflects the historical reach of the nascent United States into the western frontier following the American Revolutionary War.
Formation in the Northwest Territory
The modern framework of county formation in Illinois commenced in 1790, when the region was part of the Northwest Territory. During this period, two foundational counties were established: St. Clair and Knox. While the original Knox County eventually became a county in Indiana and is distinct from the present-day Knox County in Illinois, St. Clair County has the notable distinction of being the oldest continuously existing county within Illinois's current borders.
Statehood and Expansion
By the time Illinois achieved statehood in 1818, successive territorial governments had already established 15 counties. The process of county creation continued post-statehood, with the final county, Ford County, being established by the Illinois government in 1859. This gradual expansion reflects the state's growth and settlement patterns throughout the 19th century.
Naming Legacies
Honoring American Leaders
A significant majority of Illinois counties bear names that commemorate early American leaders. These include prominent figures from the American Revolutionary War, as well as soldiers who distinguished themselves in conflicts such as the Battle of Tippecanoe and the War of 1812. This naming convention serves as a historical tribute to those who shaped the nation's early development.
Natural and Regional Influences
Beyond national figures, some counties derive their names from natural features or from existing counties in other states, reflecting geographical connections or settler origins. Additionally, a few counties are named after early Illinois leaders who played crucial roles in the state's foundational period.
Curious Naming Anomalies
Illinois's county names also present some intriguing historical nuances. Despite having a city named Lincoln, there is no county named after Abraham Lincoln, the state's most famous son. However, there is a Douglas County, established in 1859, named after his political rival, Stephen A. Douglas. Similarly, Calhoun County, founded in 1825, is named after John C. Calhoun, known for his pro-slavery views preceding the American Civil War. This reflects the state's early settlement by many Southerners and its brief period as part of Virginia. Notably, no counties are named after Civil War heroes, as all counties were named prior to that conflict. Furthermore, two counties, DeWitt and Clinton, are both named after the prominent early 19th-century New York governor and presidential candidate, DeWitt Clinton.
Comprehensive County Data
The following table provides detailed information for each of Illinois's 102 counties, including their Federal Information Processing Standard (FIPS) code, county seat, year of establishment, origin, etymology, population, and area. This data offers a structured overview of the state's administrative divisions.
| County | FIPS Code | County Seat | Est. Year | Origin | Etymology | Population | Area (sq mi) |
|---|---|---|---|---|---|---|---|
| Adams County | 001 | Quincy | 1825 | Pike County | John Quincy Adams (1767โ1848), sixth President of the United States | 64,109 | 855 |
| Alexander County | 003 | Cairo | 1819 | Union County | William M. Alexander, settler and state representative in the Illinois General Assembly | 4,594 | 236 |
| Bond County | 005 | Greenville | 1817 | Crawford County, Edwards County, and Madison County | Shadrach Bond (1773โ1832), first Governor of Illinois | 16,576 | 380 |
| Boone County | 007 | Belvidere | 1837 | Winnebago County | Daniel Boone (1734โ1820), trailblazer of the Wilderness Road in Kentucky | 53,313 | 280 |
| Brown County | 009 | Mount Sterling | 1839 | Schuyler County | Jacob Brown (1775โ1828), successful War of 1812 army officer responsible for Great Lakes defenses | 6,307 | 305 |
| Bureau County | 011 | Princeton | 1837 | Putnam County | Pierre de Bureo, Frenchman, North American fur trader | 32,486 | 869 |
| Calhoun County | 013 | Hardin | 1825 | Pike County | John C. Calhoun (1782โ1850), South Carolina senator and seventh Vice President of the United States | 4,224 | 253 |
| Carroll County | 015 | Mount Carroll | 1839 | Jo Daviess | Charles Carroll of Carrollton (1737โ1832), signed the Declaration of Independence on behalf of Maryland | 15,444 | 445 |
| Cass County | 017 | Virginia | 1837 | Morgan County | Lewis Cass (1782โ1866), second governor of Michigan Territory, fourteenth United States Secretary of War | 12,713 | 375 |
| Champaign County | 019 | Urbana | 1833 | Vermilion County | Champaign County, Ohio, which took its name from the French for "open level country" | 212,374 | 996 |
| Christian County | 021 | Taylorville | 1839 | Sangamon County | Christian County, Kentucky, which was named after William Christian | 33,247 | 709 |
| Clark County | 023 | Marshall | 1819 | Crawford County | George Rogers Clark (1752โ1818), highest-ranking officer in the Northwest Territory during the American Revolution | 15,076 | 501 |
| Clay County | 025 | Louisville | 1824 | Wayne, Lawrence, Fayette, and Crawford County | Henry Clay (1777โ1852), Kentucky legislator who negotiated the Missouri Compromise | 12,821 | 468 |
| Clinton County | 027 | Carlyle | 1824 | Washington, Bond, and Fayette County | DeWitt Clinton (1769โ1828), Governor of New York, responsible for the construction of the Erie Canal | 37,087 | 474 |
| Coles County | 029 | Charleston | 1830 | Clark and Edgar County | Edward Coles (1786โ1868), second Governor of Illinois, responsible for the abolition of slavery in Illinois | 46,423 | 508 |
| Cook County | 031 | Chicago | 1831 | Putnam County | Daniel Pope Cook (1794โ1827), politician and first Attorney General of Illinois | 5,182,617 | 944 |
| Crawford County | 033 | Robinson | 1816 | Edwards County | William H. Crawford (1772โ1834), ninth United States Secretary of War, seventh Secretary of the Treasury | 18,388 | 443 |
| Cumberland County | 035 | Toledo | 1843 | Coles County | Disputed: Cumberland Road, which entered the county; Cumberland, Maryland; or Cumberland River in Kentucky | 10,305 | 345 |
| DeKalb County | 037 | Sycamore | 1837 | Kane County | Johann de Kalb (1721โ1780), German officer in the Continental Army who fought alongside Gilbert du Motier, marquis de Lafayette | 101,335 | 631 |
| DeWitt County | 039 | Clinton | 1839 | Macon and McLean County | DeWitt Clinton (1769โ1828), Governor of New York, responsible for the construction of the Erie Canal | 15,319 | 397 |
| Douglas County | 041 | Tuscola | 1859 | Coles County | Stephen A. Douglas (1813โ1861), prominent Illinois Democrat who engaged in debates with Abraham Lincoln | 19,824 | 416 |
| DuPage County | 043 | Wheaton | 1839 | Cook County | DuPage River | 937,142 | 327 |
| Edgar County | 045 | Paris | 1823 | Clark County | John Edgar (c. 1750โ1832), Illinois delegate to the Northwest Territory legislature; at the time, wealthiest man in Illinois | 16,398 | 623 |
| Edwards County | 047 | Albion | 1814 | Gallatin County and Madison County | Ninian Edwards (1775โ1833), third Governor of the State of Illinois and only governor of the Illinois Territory | 5,984 | 222 |
| 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 | 34,602 | 478 |
| Fayette County | 051 | Vandalia | 1821 | Bond, Wayne, Clark, Jefferson, and Crawford County | Gilbert du Motier, marquis de Lafayette (1757โ1834), French military officer who was a key factor in the American and French Revolutions. | 21,157 | 716 |
| Ford County | 053 | Paxton | 1859 | Vermilion County | Thomas Ford (1800โ1850), eighth Governor of Illinois; served during the Illinois Mormon War | 13,451 | 485 |
| Franklin County | 055 | Benton | 1818 | White County and Gallatin County | Benjamin Franklin (1706โ1790), prolific writer, inventor, and politician; key factor in the American Revolution | 37,033 | 408 |
| Fulton County | 057 | Lewistown | 1823 | Pike County | Robert Fulton (1765โ1815), inventor of the steamboat | 32,510 | 865 |
| Gallatin County | 059 | Shawneetown | 1812 | Randolph County | Albert Gallatin (1761โ1849), fourth and longest-serving United States Secretary of the Treasury | 4,690 | 322 |
| Greene County | 061 | Carrollton | 1821 | Madison County | Nathanael Greene (1742โ1786), major general in the Continental Army | 11,417 | 543 |
| Grundy County | 063 | Morris | 1841 | LaSalle County | Felix Grundy (1777โ1840), Tennessean senator who served as the thirteenth United States Attorney General | 53,835 | 418 |
| Hamilton County | 065 | McLeansboro | 1821 | White County | Alexander Hamilton (1755โ1804), first United States Secretary of the Treasury | 7,818 | 434 |
| Hancock County | 067 | Carthage | 1825 | Adams County | John Hancock (1737โ1793), first governor of the Massachusetts colony and president of the Second Continental Congress | 17,008 | 793 |
| Hardin County | 069 | Elizabethtown | 1839 | Pope County | Hardin County, Kentucky, which was named after John Hardin | 3,550 | 177 |
| Henderson County | 071 | Oquawka | 1841 | Warren County | Henderson County, Kentucky, which was named after Richard Henderson | 6,048 | 378 |
| Henry County | 073 | Cambridge | 1825 | Fulton County | Patrick Henry (1736โ1799), American Revolutionary War figure; first and sixth Governor of Virginia | 48,177 | 822 |
| Iroquois County | 075 | Watseka | 1833 | Vermilion County | Iroquois Native Americans | 26,067 | 1,117 |
| Jackson County | 077 | Murphysboro | 1816 | Randolph County and Johnson County | Andrew Jackson (1767โ1845), seventh President of the United States, United States Senator from Tennessee, and general in the War of 1812 | 53,199 | 584 |
| Jasper County | 079 | Newton | 1831 | Clay and Crawford County | Sgt. William Jasper (c. 1750โ1779), American Revolutionary War soldier popularized by Parson Weems | 9,092 | 494 |
| Jefferson County | 081 | Mount Vernon | 1819 | Edwards and White County | Thomas Jefferson (1743โ1826), 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 | 36,107 | 571 |
| Jersey County | 083 | Jerseyville | 1839 | Greene County | State of New Jersey, from which many early settlers hailed | 21,150 | 369 |
| Jo Daviess County | 085 | Galena | 1827 | Henry, Mercer, and Putnam County | Joseph Hamilton Daveiss (1774โ1811), commander of the Indiana Dragoons at the Battle of Tippecanoe | 21,528 | 600 |
| Johnson County | 087 | Vienna | 1812 | Randolph County | Richard Mentor Johnson (c. 1780โ1850), ninth Vice President of the United States and United States Senator from Kentucky | 13,320 | 343 |
| Kane County | 089 | Geneva | 1836 | LaSalle County | Elias Kane (1794โ1835), United States Senator from Illinois | 520,997 | 519 |
| Kankakee County | 091 | Kankakee | 1853 | Iroquois and Will County | Kankakee River | 106,410 | 676 |
| Kendall County | 093 | Yorkville | 1841 | LaSalle and Kane County | Amos Kendall (1789โ1869), United States Postmaster General under Presidents Andrew Jackson and Martin Van Buren | 143,171 | 320 |
| Knox County | 095 | Galesburg | 1825 | Fulton County | Gen. Henry Knox (1750โ1806), American Revolutionary War general and first United States Secretary of War | 48,716 | 716 |
| Lake County | 097 | Waukegan | 1839 | McHenry County | Lake Michigan | 718,604 | 443 |
| LaSalle County | 099 | Ottawa | 1831 | Putnam and Tazewell County | Sieur de la Salle (1643โ1687), French explorer of the Great Lakes | 108,390 | 1,135 |
| Lawrence County | 101 | Lawrenceville | 1821 | Crawford and Edwards County | Capt. James Lawrence (1781โ1813), commander of the USS Chesapeake in the War of 1812. Famous for his command "Don't give up the ship!" | 14,801 | 372 |
| Lee County | 103 | Dixon | 1839 | Ogle County | "Light Horse" Henry Lee III (1756โ1818), American Revolutionary War officer and ninth Governor of Virginia | 33,544 | 724 |
| Livingston County | 105 | Pontiac | 1837 | LaSalle and McLean County | Edward Livingston (1764โ1836), prominent jurist, Congressman from New York and Louisiana, and U.S. Secretary of State from 1831-33 | 35,375 | 1,043 |
| Logan County | 107 | Lincoln | 1839 | Sangamon County | John Logan, country doctor and early settler, and the father of John A. Logan | 27,518 | 618 |
| Macon County | 115 | Decatur | 1829 | Shelby County | Nathaniel Macon (1758โ1837), sixth Speaker of the United States House of Representatives and United States Senator from North Carolina | 100,737 | 580 |
| Macoupin County | 117 | Carlinville | 1829 | Greene County | Native American word macoupin, meaning "American lotus" | 43,895 | 862 |
| Madison County | 119 | Edwardsville | 1812 | St. Clair County and Randolph County | James Madison (1751โ1836), fourth President of the United States and principal author of the Constitution of the United States | 263,017 | 716 |
| Marion County | 121 | Salem | 1823 | Fayette and Jefferson County | Francis Marion (c. 1732โ1795), general in the American Revolutionary War known as "The Swamp Fox" | 36,437 | 572 |
| Marshall County | 123 | Lacon | 1839 | Putnam County | John Marshall (1755โ1835), fourth and longest-serving Chief Justice of the United States, wrote opinion in Marbury v. Madison establishing the principle of judicial review | 11,552 | 386 |
| Mason County | 125 | Havana | 1841 | Tazewell and Menard County | Named after Mason County, Kentucky, itself named after George Mason | 12,543 | 539 |
| Massac County | 127 | Metropolis | 1843 | Pope and Johnson County | Fort Massac, a colonial-era fort on the Ohio River | 13,627 | 237 |
| McDonough County | 109 | Macomb | 1826 | Schuyler County | Commodore Thomas Macdonough (1783โ1825), commander of American naval forces at the Battle of Plattsburgh | 26,662 | 589 |
| McHenry County | 111 | Woodstock | 1836 | Cook and LaSalle County | Major William McHenry (c. 1771โ1835), officer during several campaigns against Native Americans and was a member of the Illinois legislature | 315,959 | 603 |
| McLean County | 113 | Bloomington | 1830 | Tazewell County | John McLean (1791โ1830), United States Representative and United States Senator from Illinois (the latter from 1824โ25 and 1829โ30) | 172,069 | 1,183 |
| Menard County | 129 | Petersburg | 1839 | Sangamon County | Pierre Menard (1766โ1844), prominent early settler and first Lieutenant Governor of Illinois | 11,963 | 314 |
| Mercer County | 131 | Aledo | 1825 | Schuyler County | Hugh Mercer (1726โ1777), British officer in the Seven Years' War and general in the Continental Army during the American Revolutionary War | 15,292 | 561 |
| Monroe County | 133 | Waterloo | 1816 | Randolph County and St. Clair County | James Monroe (1758โ1831), seventh United States Secretary of State, eighth United States Secretary of War, Governor of Virginia, and fifth President of the United States | 34,969 | 385 |
| Montgomery County | 135 | Hillsboro | 1821 | Bond and Madison County | Gen. Richard Montgomery (1738โ1775), brigadier-general in the Continental Army who led the unsuccessful invasion of Canada | 27,615 | 703 |
| Morgan County | 137 | Jacksonville | 1823 | Sangamon County | Gen. Daniel Morgan (1736โ1802), successful tactician in the American Revolutionary War and later United States Representative from Virginia | 32,618 | 568 |
| Moultrie County | 139 | Sullivan | 1843 | Shelby and Macon County | Gen. William Moultrie (1730โ1805), American Revolutionary War general and Governor of South Carolina | 14,365 | 335 |
| Ogle County | 141 | Oregon | 1836 | Jo Daviess | Joseph Ogle (1737โ1821), early settler in southwest Illinois, who helped found the first Methodist church in Illinois | 51,345 | 758 |
| Peoria County | 143 | Peoria | 1825 | Fulton County | The Peoria Native American tribe | 179,630 | 618 |
| Perry County | 145 | Pinckneyville | 1827 | Randolph and Jackson County | Cmdre. Oliver Hazard Perry (1785โ1819), American naval officer who led the victorious American forces at the Battle of Lake Erie | 20,272 | 441 |
| 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 | 16,628 | 439 |
| Pike County | 149 | Pittsfield | 1821 | Madison, Bond, and Clark County | Zebulon Pike (1779โ1813), early explorer of the American Southwest, namesake of Pikes Peak | 14,258 | 831 |
| Pope County | 151 | Golconda | 1816 | Gallatin and Johnson County | Nathaniel Pope (1784โ1850), early Delegate from Illinois Territory to Congress and judge on the United States District Court for the District of Illinois | 3,703 | 368 |
| Pulaski County | 153 | Mound City | 1843 | Alexander and Johnson County | Gen. Casimir Pulaski (1745โ1779), Polish American general of cavalry in the American Revolutionary War | 4,879 | 199 |
| Putnam County | 155 | Hennepin | 1825 | Fulton County | Gen. Israel Putnam (1718โ1790), commander of American forces at the Battle of Bunker Hill | 5,633 | 160 |
| Randolph County | 157 | Chester | 1795 | St. Clair County | Edmund Randolph (1753โ1813), first Attorney General of the United States, and briefly United States Secretary of State | 29,903 | 575 |
| Richland County | 159 | Olney | 1841 | Clay and Lawrence County | Richland County, Ohio, itself named for its rich soil | 15,362 | 360 |
| Rock Island County | 161 | Rock Island | 1831 | Jo Daviess County | Rock Island | 142,731 | 427 |
| Saline County | 165 | Harrisburg | 1847 | Gallatin County | The Saline River and salt springs in the county | 22,826 | 379 |
| Sangamon County | 167 | Springfield | 1821 | Madison and Bond County | Sangamon River | 194,345 | 868 |
| Schuyler County | 169 | Rushville | 1825 | Pike and Fulton County | Gen. Philip Schuyler (1733โ1804), American Revolutionary War general and United States Senator from New York | 6,750 | 437 |
| Scott County | 171 | Winchester | 1839 | Morgan County | Scott County, Kentucky, itself named after Charles Scott | 4,880 | 250 |
| Shelby County | 173 | Shelbyville | 1827 | Fayette County | Isaac Shelby (1750โ1826), soldier in the American Revolutionary War and War of 1812; first and fifth Governor of Kentucky | 20,542 | 758 |
| St. Clair County | 163 | Belleville | 1790 | original two counties | Arthur St. Clair (1737โ1818), major general in the American Revolutionary War and first Governor of the Northwest Territory | 251,149 | 657 |
| Stark County | 175 | Toulon | 1839 | Knox and Putnam County | Gen. John Stark (1728โ1822), general in the American Revolutionary War, called the "Hero of Bennington" | 5,272 | 288 |
| Stephenson County | 177 | Freeport | 1837 | Jo Daviess and Winnebago County | Benjamin Stephenson (1769โ1822), representative of Illinois Territory in the United States Congress from 1814 to 1816 | 43,088 | 564 |
| Tazewell County | 179 | Pekin | 1827 | Sangamon County | Littleton Waller Tazewell (1774โ1860), United States Senator from (and later governor of) Virginia | 129,821 | 646 |
| Union County | 181 | Jonesboro | 1818 | Johnson County | The union of the United States | 16,886 | 413 |
| Vermilion County | 183 | Danville | 1826 | Edgar County | The Vermilion River | 71,106 | 898 |
| Wabash County | 185 | Mount Carmel | 1824 | Edwards County | The Wabash River | 10,979 | 223 |
| Warren County | 187 | Monmouth | 1825 | Schuyler County | Joseph Warren (1741โ1775), played a role in American Patriot movements, a prominent early fatality in the American Revolutionary War | 16,217 | 542 |
| Washington County | 189 | Nashville | 1818 | St. Clair County | George Washington (1732โ1799), commander-in-chief of American forces in the American Revolutionary War and first President of the United States | 13,535 | 562 |
| Wayne County | 191 | Fairfield | 1819 | Edwards County | Gen. "Mad" Anthony Wayne (1745โ1796), major general in the United States Army in the American Revolutionary War and the Northwest Indian War | 15,928 | 713 |
| White County | 193 | Carmi | 1815 | Gallatin County | Isaac White (1776โ1811), resident of Illinois who enlisted in the Indiana militia and was killed at the Battle of Tippecanoe | 13,395 | 494 |
| Whiteside County | 195 | Morrison | 1836 | Jo Daviess and Henry County | Samuel Whiteside (1783โ1868), state legislator and militia leader | 54,657 | 684 |
| Will County | 197 | Joliet | 1836 | Cook and Iroquois County | Conrad Will (1779โ1835), physician, local businessman and longtime member of the state legislature | 708,583 | 835 |
| Williamson County | 199 | Marion | 1839 | Franklin County | Williamson County, Tennessee, which was named for Hugh Williamson | 67,064 | 420 |
| Winnebago County | 201 | Rockford | 1836 | Jo Daviess County | Winnebago Native Americans | 283,790 | 513 |
| Woodford County | 203 | Eureka | 1841 | Tazewell and McLean County | Woodford County, Kentucky, which was named for William Woodford | 38,290 | 527 |
Defunct Counties
Renamed: Dane County
One notable instance of a defunct county is Dane County. Established in the early history of Illinois, this county was subsequently renamed in 1840 to what is now known as Christian County. Such renamings often reflect shifts in political sentiment, prominent local figures, or a desire for a more fitting geographical or historical designation.
Reassigned: Original Knox County
The original Knox County, Illinois, ceased to exist with the formal establishment of the Illinois Territory in 1809. More precisely, its territory was absorbed and became part of Knox County, Indiana, as administrative boundaries were redrawn during the territorial period. It is important to note that this original entity is entirely unrelated to the modern Knox County, Illinois, which was formed much later and from different territorial divisions.
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This page was generated by an Artificial Intelligence and is intended for informational and educational purposes only. The content is based on a snapshot of publicly available data from Wikipedia and may not be entirely accurate, complete, or up-to-date.
This is not official governmental or legal advice. The information provided on this website is not a substitute for consulting official state or county records, legal counsel, or professional geographical and historical research. Always refer to authoritative sources for specific administrative, legal, or historical inquiries regarding Illinois counties. Never disregard official information because of something you have read on this website.
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