| County | Origin of Name | Date of Organization | County Seat |
|---|---|---|---|
| Adams | President John Quincy Adams | March1, 1836 | Decatur |
| Allen | Colonel John Allen of Kentucky | April 1, 1824 | Fort Wayne |
| Bartholomew | Gen. Joseph Bartholomew, U. S. Senator | February 12, 1821 | Columbus |
| Benton | Thomas H. Benton, U. S. Senator | February 18, 1840 | Fowler |
| Blackford | Judge Isaac Blackford | April 2, 1838 | Hartford City |
| Boone | Daniel Boone | April 1, 1830 | Lebanon |
| Brown | Gen. Jacob Brown of War of 1812 | April 1, 1836 | Nashville |
| Carroll | Charles Carroll of Maryland | May 1, 1828 | Delphi |
| Cass | Gen. Lewis Cass, Governor of Michigan | April 14, 1829 | Logansport |
| Clark | Gen. George Rogers Clark | February 3, 1801 | Jeffersonville |
| Clay | Henry Clay | April 1, 1825 | Brazil |
| Clinton | DeWitt Clinton, Governor of New York | March 1, 1830 | Frankfort |
| Crawford | Col. William Crawford | March 1, 1818 | English |
| Daviess | Col. Joseph H. Daviess | February 15, 1817 | Washington |
| Dearborn | Gen. Henry Dearborn, Sec. of War | March 7, 1803 | Lawrenceburg |
| Decatur | Commodore Stephen Decator | March 4, 1822 | Greensburg |
| DeKalb | Baron DeKalb | May 1, 1837 | Auburn |
| Delaware | Delaware Indian tribe | April 1, 1827 | Muncie |
| Dubois | Toussaint Dubois | February 1, 1818 | Jasper |
| Elkhart | Elkhart Indian tribe | April 1,1830 | Goshen |
| Fayette | Marquis de Lafayette | January 1, 1819 | Connersville |
| Floyd |
Davis Floyd (Previously identified as Col. John Floyd of Virginia - learn more) | February 1, 1819 | New Albany |
| Fountain | Maj. Fountain of Kentucky | April 1, 1826 | Covington |
| Franklin | Benjamin Franklin | January 1, 1811 | Brookville |
| Fulton | Robert Fulton | April 1, 1836 | Rochester |
| Gibson | John Gibson, Governor of Indiana Territory | April 1, 1813 | Princeton |
| Grant | Capts.. Samuel and Moses Grant of Kentucky | April 1, 1831 | Marion |
| Greene | Gen. Nathaniel Greene of American Revolution | February 5, 1821 | Bloomfield |
| Hamilton | Alexander Hamilton | April 7, 1823 | Noblesville |
| Hancock | John Hancock | March 1, 1828 | Greenfield |
| Harrison | William Henry Harrison, Territorial Governor | December 1, 1808 | Corydon |
| Hendricks | William Hendricks, Governor of Indiana | April 1, 1824 | Danville |
| Henry | Patrick Henry | June 1, 1822 | New Castle |
| Howard | Gen. T. A. Howard | May 1, 1844 | Kokomo |
| Huntington | Samuel Huntington | February 2, 1832 | Huntington |
| Jackson | Gen. Andrew Jackson | January 1, 1816 | Brownstown |
| Jasper | Sergeant William Jasper, Revolutionary War | March 15, 1838 | Rensselaer |
| Jay | John Jay, Governor of New York | March 1, 1836 | Portland |
| Jefferson | Thomas Jefferson | January 1, 1811 | Madison |
| Jennings | Jonathon Jennings, 1st Governor of Indiana | February 1, 1817 | Vernon |
| Johnson | Judge John Johnson, Indiana Supreme Court | May 5, 1823 | Franklin |
| Knox | Gen. Knox, Secretary of War | June 20,1790 | Vincennes |
| Kosciusko | Kosciusko, Hero of American Revolution | June 1, 1836 | Warsaw |
| LaGrange | Name of Lafayette's home near Paris | April 1, 1832 | LaGrange |
| Lake | Lake Michigan | February 15, 1837 | Crown Point |
| La Porte | French for "the door" or "the port" | April 1, 1832 | La Porte |
| Lawrence | Capt. James Lawrence | March 16, 1818 | Bedford |
| Madison | James Madison | July 1, 1823 | Anderson |
| Marion | Gen. Francis Marion | April 1, 1822 | Indianapolis |
| Marshall | Chief Justice John Marshall | April 1, 1836 | Plymouth |
| Martin | Maj. John T. Martin of Kentucky | February 1, 1820 | Shoals |
| Miami | Miami Indian tribe | March 1, 1834 | Peru |
| Monroe | James Monroe | April 10, 1818 | Bloomington |
| Montgomery | Gen. Richard Montgomery | March 1, 1823 | Crawfordsville |
| Morgan | Gen. Daniel Morgan | February 15, 1822 | Martinsville |
| Newton | Sgt. John Newton | December 8, 1859 | Kentland |
| Noble | James Noble, 1st U. S. Senator from Indiana | March 1, 1836 | Albion |
| Ohio | Ohio River | March 1, 1844 | Rising Sun |
| Orange | Orange County, North Carolina | February 1, 1816 | Paoli |
| Owen | Col. Abraham Owen, Tippecanoe Battle casualty | January 1, 1819 | Spencer |
| Parke | Benjamin Parke, 1st territorial delegate to Congress | April 2, 1821 | Rockville |
| Perry | Commodore Oliver H. Perry | November 1, 1814 | Tell City |
| Pike | Gen. Zebulon M. Pike | February 1, 1817 | Petersburg |
| Porter | Commodore David Porter, War of 1812 | February 1, 1836 | Valparaiso |
| Posey | Gen.Thomas Posey | November 1, 1814 | Mt. Vernon |
| Pulaski | Count Casimir Pulaski, American Revolution | May 6, 1839 | Winamac |
| Putnam | Gen. Israel Putnam | April 1, 1822 | Greencastle |
| Randolph | Thomas Randolph or Randolph Co. North Carolina | August 10, 1818 | Winchester |
| Ripley | Gen. E. W. Ripley, War of 1812 | April 10, 1818 | Versailles |
| Rush | Dr. Benjamin Rush | April 1, 1822 | Rushville |
| Scott | Gen. Charles Scott, Governor of Kentucky | February 1, 1820 | Scottsburg |
| Shelby | Isaac Shelby | April 1, 1822 | Shelbyville |
| Spencer | Capt. Spier Spencer | February 1, 1818 | Rockport |
| Starke | General Starke | January 15, 1850 | Knox |
| St. Joseph | St. Joseph River | April 1, 1830 | South Bend |
| Steuben | Baron Steuben of the Revolutionary War | May 1, 1837 | Angola |
| Sullivan | General Daniel Sullivan | January 15, 1817 | Sullivan |
| Switzerland | Switzerland, native land of first settlers | October 1, 1814 | Vevay |
| Tippecanoe | Tippecanoe River and battleground | March 1, 1826 | Lafayette |
| Tipton | Gen. John Tipton | May 1, 1844 | Tipton |
| Union | Symbolical of union of interests | February 1, 1821 | Liberty |
| Vanderburgh | Henry Vanderburgh, Territorial judge | February 1, 1818 | Evansville |
| Vermillion | Vermillion River | February 1, 1824 | Newport |
| Vigo | Col. Francis Vigo | February 15, 1818 | Terre Haute |
| Wabash | Wabash River | March 1, 1835 | Wabash |
| Warren | Gen. Joseph Warren, American Revolution | March 1, 1827 | Williamsport |
| Warrick | Capt. Jacob Warrick | April 1, 1813 | Boonville |
| Washington | George Washington | January 17, 1814 | Salem |
| Wayne | Gen. Anthony Wayne | January 1, 1811 | Richmond |
| Wells | Capt. William A. Wells | May 1, 1837 | Bluffton |
| White | Col. Isaac White | April 1, 1834 | Monticello |
| Whitley | Col. William Whitley | April 1, 1838 | Columbia City |
| Based on "Here Is Your Indiana Government" 1997-98 edition, published by Indiana Chamber of Commerce, Indianapolis, IN | |||
