| County name (years established) | State | Name origin | Modern counties |
|---|
| Baine County (1866–1868) | Alabama | David W. Baine, Confederate General [1] | Etowah County |
| Baker County (1868–1874) | Alfred Baker, founder of Clanton, Alabama [2] | Chilton County |
| Benton County (1832–1858) | Thomas Hart Benton, U.S. Senator from Missouri [3] | Calhoun County |
| Cahawba County (1818–1820) | The Cahawba (Cahaba) River [4] | Bibb County |
| Cotaco County (1818–1821) | Cotaco Creek, possibly derived from the Cherokee "ikati" (swamp) and "kunahita" (long) [5] [6] | Morgan County |
| Decatur County (1821-1825) | Stephen Decatur, Naval Commodore | Madison and Jackson counties |
| Hancock County (1850–1858) | John Hancock, Founding Father and Governor of Massachusetts [7] | Winston County |
| Jones County (1867) | Elliot P. Jones, Alabama Legislature member [8] | Lamar County |
| Jones County (1868) | Josiah Jones, former legislator and local political leader [8] | Covington County |
| Sanford County (1868–1877) | Henry C. Sanford, Alabama Senate member [8] | Lamar County |
| Chugiak–Eagle River Borough (1974–1975) | Alaska | Chugiak, Anchorage and Eagle River, Anchorage [9] | Municipality of Anchorage |
| Greater Anchorage Area Borough (1964–1975) | Anchorage [10] | Municipality of Anchorage |
| Greater Juneau Area Borough (1963–1970) | Juneau [11] | City and Borough of Juneau |
| Greater Sitka Borough (1963–1971) | Sitka [12] | City and Borough of Sitka |
| Skagway-Hoonah-Angoon Census Area (1992–2007) | Angoon, Hoonah, and Skagway [13] | Municipality of Skagway and Hoonah–Angoon Census Area |
| Skagway-Yakutat-Angoon Census Area (1980–1992) | Angoon, Skagway, and Yakutat [14] | Municipality of Skagway, City and Borough of Yakutat and Hoonah–Angoon Census Area |
| Valdez–Cordova Census Area (1980–2019) | Cordova and Valdez [15] | Chugach Census Area and Copper River Census Area |
| Wade Hampton Census Area (1980–2015) | Wade Hampton III, Confederate officer and South Carolina politician [16] | Kusilvak Census Area |
| Pah-Ute County (1865–1871) | Arizona | Southern Paiute people, a Native American tribe which inhabited the area [17] | Mohave County and Clark County, Nevada |
| Clayton County (1873–1875) | Arkansas | Either John M. Clayton, Arkansas Senate member, or Powell Clayton, U.S. Senator from Arkansas [18] [19] | Clay County |
| Dorsey County (1873–1885) | Stephen Wallace Dorsey, U.S. Senator from Arkansas [20] | Cleveland County |
| Lovely County (1827–1828) | Major William Lewis Lovely, Indian agent to the Arkansas Cherokee, who managed the transaction of the county's land [21] | Washington County and Oklahoma |
| Miller County (1820–1838) | James Miller, Governor of Arkansas Territory [22] | Fannin County |
| Sarber County (1871–1875) | John Sarber, Arkansas Senate member [23] | Logan County |
| Branciforte County (1850) | California | Branciforte, a Spanish colonial settlement, itself named for the 1st Marquess of Branciforte [24] | Santa Cruz County |
| Klamath County (1851–1874) | A derivative of the Native "Athlameth" meaning people [25] | Humboldt and Siskiyou Counties |
| Guadaloupe County (1861) | Colorado | Unknown, possibly Our Lady of Guadalupe | Conejos County |
| Greenwood County (1870–1874) | Unknown | Elbert and Bent Counties |
| Carbonate County (1879) | Unknown | Chaffee and Lake Counties |
| Uncompahgre County (1883) | The Uncompahgre Ute band of Ute people | Ouray County |
| South Arapahoe County (1902–1903) | Arapahoe County, from which it was created [26] | Arapahoe County |
| Westmoreland County (1776–1786) | Connecticut | The town of Westmoreland in the Wyoming Valley [27] | Luzerne County |
| Washington County (1791–1871) | District of Columbia | George Washington, U.S. President [28] | Washington, D.C. |
| Benton County (1844–1850) | Florida | Thomas Hart Benton, U.S. Senator from Missouri [29] | Hernando County |
| Fayette County (1832–1834) | Marquis de Lafayette, Revolutionary War general and French politician [30] | Jackson, Calhoun, and Gulf Counties |
| Mosquito County (1824–1845) | Los Mosquitos, the Spanish name for Florida's east coast [31] | Volusia, Brevard, Indian River, St. Lucie, Martin, Seminole, Osceola, Orange, Lake, Polk and Palm Beach Counties |
| New River County (1858–1861) | New River, a tributary of the Santa Fe River [32] | Bradford County |
| Bourbon County (1785–1788) | Georgia | House of Bourbon, the European dynasty [33] | |
| Campbell County (1828–1931) | Duncan G. Campbell, legislator and U.S. commissioner [34] | Douglas, Milton and Fulton Counties |
| Cass County (1832–1861) | Lewis Cass, Secretary of War [35] | Bartow County |
| Kinchafoonee County (1853–1856) | Kinchafoonee Creek, Creek for "mortar nutshells", a type of nutcracker [36] | Webster County |
| Milton County (1857–1931) | John Milton, Continental Army lieutenant and Georgia Secretary of State [37] | Fulton County |
| Walton County (1803–1818) | George Walton, U.S. Senator from Georgia [38] | Buncombe County |
| Alturas County (1864–1895) | Idaho | Spanish for "mountainous heights" [39] | Blaine and Lincoln Counties |
| Lah-Toh County (1864–1867) | Latah Creek, Nez Perce for "the place of pine trees and pestle" [40] | Kootenai, Latah and Nez Perce Counties |
| Logan County (1889–1895) | Unknown | Lincoln County |
| Richardville County (1844) | Indiana | Jean Baptiste Richardville, civil chief of the Miami people [41] | Howard County |
| Slaughter County (1838–1839) | Iowa | William B. Slaughter, secretary of Wisconsin Territory [42] | Washington County |
| Bancroft County (1851–1857) | George Bancroft, Secretary of the Navy [43] | Kossuth County |
| Crocker County (1871–1872) | Marcellus M. Crocker, Union Army Brigadier general [44] | Kossuth County |
| Wahkaw County (1851–1853) | Sioux for "big medicine" [45] | Woodbury County |
| Billings County (1873–1874) | Kansas | Either as a joke or for N. H. Billings, county attorney [46] | Norton County |
| Breckinridge County (1873–1881) | John C. Breckinridge, Kentucky politician and U.S. Vice President [47] | Lyon County |
| Buffalo County (1873–1881) | American bison, which were common in the area [48] | Gray and Finney Counties |
| Davis County (1855–1889) | Jefferson Davis, then-Secretary of War [49] | Geary County |
| Foote County (1873–1881) | Most likely Andrew Hull Foote, Union Naval officer [50] | Gray County |
| Garfield County (1887–1893) | James A. Garfield, U.S. President [51] | Finney County |
| Godfrey County (1855–1861) | Either Bill Godfrey, trader among the Osage Nation, or Gabriel Godfrey, subagent to the Potawatomi [52] | Chautauqua and Elk Counties |
| Howard County (1867–1875) | Oliver Otis Howard, Union Army general [53] | Chautauqua and Elk Counties |
| Hunter County (1855–1864) | Most likely Robert M. T. Hunter, Virginia politician [54] | Butler, Cowley, Sedgwick, Sumner, Elk, Chautauqua, and Greenwood Counties |
| Irving County (1860–1864) | Washington Irving, author [55] | Butler County |
| Kansas County (1873–1883) | The Kaw (Kansas) tribe [56] | Seward County |
| Madison County (1855–1861) | Most likely James Madison, U.S. President [57] | Lyon and Greenwood Counties |
| Otoe County (1860–1864) | Otoe, a Native American people [58] | Butler County |
| Peketon County (1859–1861) | Unknown, possibly a Sauk word for "flat land" [59] | Most of south west Kansas |
| Sequoyah County (1873–1883) | Sequoyah, creator of the Cherokee syllabary [60] | Finney County |
| Seward County (1861–1867) | Most likely William H. Seward, U.S. Secretary of State [61] | Chautauqua, Elk, and Greenwood Counties |
| Shirley County (1860–1867) | Either William Shirley, colonial governor of Massachusetts, or Jane Shirley, a "lady of questionable character" [62] | Cloud County |
| Washington County (1855–1857) | George Washington, U.S. President [63] | Most of south west Kansas |
| Beckham County (1904) | Kentucky | J. C. W. Beckham, Governor of Kentucky [64] | Carter County |
| Biloxi Parish (1811-1812) | Louisiana | Unknown | Coastal Mississippi |
| Carroll Parish (1838–1877) | Charles Carroll of Carrollton, U.S. Senator from Maryland [65] | East Carroll and West Carroll Parishes |
| Feliciana Parish (1810–1824) | Marie Felicité, wife of Viceroy of New Spain Bernardo de Gálvez [66] | East Feliciana and West Feliciana Parishes |
| Pascagoula Parish (1811–1812) | Unknown | Coastal Mississippi |
| Warren Parish (1811–1814) | Unknown | Ouachita and Concordia Parishes |
| Isle Royale County (1875–1897) | Michigan | Isle Royale, an island in Lake Superior | Keweenaw County |
| Manitou County (1855–1895) | North and South Manitou Islands, in Lake Michigan | Leelanau County |
| Michilimackinac County (1818–1849) | Mi-shi-ne-macki-nong, the Ojibwe name for Mackinac Island, derived from the Mi-shi-ne-macki naw-go tribe [67] | Mackinac County |
| Tonedagana County (1840-1843) | Derived from a Odawa war chief from the Cross Village area [68] | Emmet County |
| Manomin County (1857–1858) | Minnesota | A variant spelling of "manoomin", the Ojibwe term for wild rice [69] | Anoka County |
| Monongalia County (1861-1870) | Unknown | Kandiyohi County |
| Pearl County (1872–1878) | Mississippi | Pearl River, a river in the area | Pearl River County |
| Allen County (1843–1845) | Missouri | Unknown | Atchison County |
| Ashley County (1843–1845) | William Henry Ashley, Lieutenant Governor of Missouri [70] | Texas County |
| Decatur County (1843–1845) | Stephen Decatur, Naval Commodore [71] | Ozark County |
| Dodge County (1849–1853) | Unknown [72] | Putnam County |
| Kinderhook County (1841–1843) | Kinderhook, New York, birthplace of Martin Van Buren [71] | Camden County |
| Lillard County (1821–1825) | James Lillard, constitutional convention and Missouri General Assembly member [71] | Camden County |
| Niangua County (1842–1844) | Niangua River, from the Native American "nehemgar", meaning "a river of numerous springs or sources" [73] | Dallas County |
| Rives County (1834–1841) | William Cabell Rives, Senator from Virginia [73] | Henry County |
| Edgerton County (1865–1867) | Montana | Sidney Edgerton, Governor of Montana Territory [74] | Lewis and Clark County |
| Bullfrog County (1987–1989) | Nevada | Bullfrog Mining District, itself named for the gold ore there being colored like a bullfrog [75] | Nye County |
| Lake County (1861–1862) | A number of lakes in the area, such as Honey Lake, Pyramid Lake, and Winnemucca Lake [76] | Lassen County and Washoe County |
| Ormsby County (1861–1969) | Major William Ormsby, early settler of Carson City and militia leader during the Pyramid Lake War [77] | Consolidated Municipality of Carson City |
| Roop County (1862–1864) | Isaac Roop, governor of Nevada Territory [76] | Lassen County and Washoe County |
| Santa Ana County (1852–1876) | New Mexico | Unknown | Bernalillo and McKinley Counties |
| Charlotte County (1772–1784) | New York | Charlotte of Mecklenburg-Strelitz, wife of George III of the United Kingdom [78] | Washington County |
| Tryon County (1772–1784) | William Tryon, colonial governor of New York [79] | Montgomery County |
| Glasgow County (1791–1799) | North Carolina | James Glasgow, North Carolina Secretary of State [80] | Greene County |
| Wallace County (1883–1896) | North Dakota | Unknown | McKenzie County |
| County E (1891–1892) | Oklahoma | Temporary name given by an Act of Congress [81] | Ellis, Roger Mills and Woodward Counties |
| Day County (1892–1907) | Charles Day, a contractor who built the courthouse at Ioland [82] | Ellis, Roger Mills and Woodward Counties |
| Swanson County (1910–1911) | Claude A. Swanson, Governor of Virginia [83] | Comanche County |
| Umpqua County (1851–1862) | Oregon | The Umpqua River, a river in the area [84] | Douglas and Coos Counties |
| Ontario County (1810–1812) | Pennsylvania | Unknown | Bradford County |
| Claremont County (1785–1800) | South Carolina | Unknown [85] | Sumter County |
| Granville County (1785–1798) | John Granville, Earl of Bath, British landowner [86] | Beaufort and Colleton Counties |
| Lewisburg County (1785–1791) | Unknown | Orangeburg County |
| Liberty County (1785–1798) | The freedom gained due to the American Revolution [87] | Marion County |
| Orange County (1785–1791) | William of Orange, King of England [88] | Orangeburg County |
| Salem County (1791–1800) | Unknown, probably after Salem Black River Presbyterian Church [89] | Sumter County |
| Winton County (1785–1800) | Unknown | Barnwell County |
| Winyah County (1785–1800) | Winyah Bay, an estuary in the area [90] | Georgetown County |
| Armstrong County (1895–1953) | South Dakota | Moses K. Armstrong, delegate to the House of Representatives for Dakota at-large [91] | Dewey, Stanley, and Ziebach Counties |
| Lugenbeel County (1889–1909) | Pinkney Lugenbeel, United States Army officer [92] | Bennett and Todd Counties |
| Pyatt County (1883–1895) | Unknown | Dewey, Stanley, and Ziebach Counties |
| Shannon County (1875–2015) | Peter C. Shannon, Chief Justice of the Supreme Court of the Dakota Territory [93] | Oglala Lakota County |
| Washabaugh County (1883–1983) | Frank J. Washabaugh, member of the Dakota Territorial Council [94] | Jackson County |
| Washington County (1883–1943) | George Washington, U.S. President [94] | Jackson, Pennington and Shannon Counties |
| James County (1871–1919) | Tennessee | Rev. Jesse J. James, father of Elbert Abdiel James, who introduced legislation to form the county [95] | Hamilton County |
| Buchanan County (1858–1861) | Texas | James Buchanan, U.S. President [96] | Stephens County |
| Buchel County (1887–1897) | Augustus Buchel, Confederate colonel [97] | Brewster County |
| Dawson County (1858–1866) | Nicholas Mosby Dawson, Republic of Texas military leader and commander in the Dawson massacre [98] | Uvalde and Kinney Counties |
| Davis County (1861–1871) | Jefferson Davis, President of the Confederate States of America [99] | Cass County |
| Encinal County (1856–1899) | Unknown | Webb County |
| Foley County (1887–1897) | Unknown | Brewster County |
| Harrisburg County (1836–1839) | Harrisburg, Houston, itself named after Harrisburg, Pennsylvania and its founder, John Richardson Harris [100] | Harris County |
| Navasota County (1841–1842) | Unknown | Brazos County |
| Wegefarth County (1873–1876) | Conrad Wegefarth, president of the Texas Immigrant Aid and Supply Company [101] | Collingsworth, Donley, Briscoe, Childress, Gray, Hall, and Wheeler Counties |
| Cedar County (1856–1862) | Utah | Cedar trees growing in the area (which are actually juniper trees) [102] [103] | Utah County |
| Desert County (1852–1862) | The surrounding desert | Box Elder and Tooele Counties |
| Greasewood County (1856–1862) | Sarcobatus (greasewood) plant, which grew in the area [104] | Box Elder County |
| Green River County (1852–1872) | The Green River, a Colorado River tributary [105] | Cache, Weber, Morgan, Davis, Wasatch, Summit, Duchesne, Carbon, and Utah Counties |
| Malad County (1856–1862) | The Malad River, from the French "malade" meaning sick [106] | Box Elder County |
| Rio Virgen County (1869–1872) | The Virgin River, a Colorado River tributary [107] | Washington County |
| Shambip County (1856–1862) | Unknown, possibly the Goshute word for the bulrush plant [108] | Tooele County |
| Elizabeth City County (1634–1952) | Virginia | Elizabeth Stuart, Queen consort of Bohemia [109] | City of Hampton |
| Fincastle County (1772–1776) | Either Viscount of Fincastle, Scottish Peer, Earl of Dunmore, governor of Virginia, or Fincastle, Virginia [110] | Montgomery and Washington Counties |
| Illinois County (1778–1784) | The Algonquian word "ilinouek", meaning "ordinary speaker" [111] | Ohio and Illinois |
| Kentucky County (1778–1784) | The Iroquois word "ken-tah-ten", meaning either "land of tomorrow", "meadow", "prairie", or "the river of blood" [112] | Kentucky |
| Nansemond County (1646–1972) | The Nansemond indigenous people [113] | City of Suffolk |
| City of Nansemond (1972–1974) |
| Norfolk County (1691–1963) | Most likely Norfolk, home county of Captain Adam Thoroughgood [114] | City of Chesapeake |
| Princess Anne County (1691–1963) | Queen Anne, Queen of Great Britain and Ireland [115] | City of Virginia Beach |
| Warwick County (1634–1952) | Either Robert Rich, Earl of Warwick, or Warwick, a town in the UK [116] | City of Newport News |
| City of Warwick (1952–1958) |
| Yohogania County (1776–1779) | The Youghiogheny River, a tributary of the Monongahela River | Westmoreland County |
| Chehalis County (1854–1915) | Washington | The Chehalis people, meaning "sand" or "inlanders" [117] | Grays Harbor County |
| Quillehuyte County (1868–1869) | Most likely the Quileute natives | Clallam and Jefferson Counties |
| Sawamish County (1868–1869) | The Sahewamish natives [118] | Mason County |
| Slaughter County (1857) | Lieutenant William A. Slaughter, who had been killed at White River a year prior [119] | Kitsap County |
| La Pointe County (1845–1866) | Wisconsin | La Pointe, Wisconsin | Itasca, Washington, Ramsey, Benton, Douglas, Ashland, and Bayfield Counties |
| Carter County (1867–1869) | Wyoming | William Alexander Carter, a sutler from Fort Bridger, Wyoming [120] | Sweetwater County |
| Pease County (1875–1879) | E. L. Pease, President of the Territorial Legislative Council [121] | Johnson County |
