| Län | FIPS-kod | Länets huvudort | Etablerad | Bildad av | Betydelse av namnet | Befolkning | Område | Karta |
| Aurora län | 003 | Plankinton | 1881 | Cragin och Wetmore län | Aurora, romersk gryningsgudinna | 7003271000000000000♠2,710 | 7002708000000000000♠708 kvadratkilometer
(70031834000000000000000♠1,834 km2 ) | 
|
| Beadle County | 005 | Huron | 1879 | länen Buchard, Clark, Kingsbury och Spink | William Henry Harrison Beadle, chefslantmätare i Dakota Territory | 7004173980000000000♠17,398 | 70031259000000000000000♠1,259 sq mi
(7003326100000000000♠3,261 km2 ) | 
|
| Bennett County | 007 | Martin | 1909 | länen Lugenbeel, Shannon, Washabaugh och Washington | Granville G. Bennett, domare i Dakota Territory's högsta domstol. | 7003343100000000000♠3,431 | 70031185000000000000000♠1,185 sq mi
(70033069000000000000000♠3,069 km2 ) | 
|
| Bon Homme län | 009 | Tyndall | 1862 | Oorganiserat territorium | Franskt ord som betyder "god man". | 7003707000000000000♠7,070 | 7002563000000000000♠563 kvadratkilometer
(70031458000000000000000♠1,458 km2 ) | 
|
| Brookings län | 011 | Brookings | 1862 | Oorganiserat territorium | Wilmot Brookings (1830-1905), domare i Dakota Territory Supreme Court | 7004319650000000000♠31,965 | 7002794000000000000♠794 kvadratkilometer
(70032056000000000000000♠2,056 km2 ) | 
|
| Brown County | 013 | Aberdeen | 1879 | Beadle County | Alfred Brown, territoriell lagstiftare | 7004365310000000000♠36,531 | 70031713000000000000000♠1,713 sq mi
(70034437000000000000000♠4,437 km2 ) | 
|
| Brule County | 015 | Chamberlain | 1875 | Charles Mix County | Brulé Sioux indianer | 7003525500000000000♠5,255 | 70028190000000000000000♠819 kvadratkilometer
(70032121000000000000000♠2,121 km2 ) | 
|
| Buffalo County | 017 | Gann-dalen | 1873 | Oorganiserat territorium | Amerikansk bison | 7003191200000000000♠1,912 | 70024710000000000000000♠471 kvadratkilometer
(70031220000000000000000♠1 220 km2 ) | 
|
| Butte County | 019 | Belle Fourche | 1883 | Harding | Bergkullar i regionen | 7004101100000000000♠10,110 | 70032249000000000000000♠2,249 sq mi
(70035825000000000000000♠5,825 km2 ) | 
|
| Campbell County | 021 | Mound City | 1873 | Buffalo | Newton B. Campbell, territoriell lagstiftare | 7003146600000000000♠1,466 | 7002736000000000000♠736 kvadratkilometer
(70031906000000000000000♠1,906 km2 ) | 
|
| Charles Mix County | 023 | Andes-sjön | 1862 | Oorganiserat territorium | Charles Eli Mix, kommissionär för indianska frågor | 7003912900000000000♠9,129 | 70031098000000000000000♠1,098 sq mi
(70032844000000000000000♠2,844 km2 ) | 
|
| Clark County | 025 | Clark | 1873 | Hanson | Newton Clark, territoriell lagstiftare | 7003369100000000000♠3,691 | 7002958000000000000♠958 kvadratkilometer
(70032481000000000000000♠2,481 km2 ) | 
|
| Clay County | 027 | Vermillion | 1862 | Oorganiserat territorium | Henry Clay (1777 - 1852), amerikansk senator från Kentucky och framstående politisk person på 1800-talet. | 7004138640000000000♠13,864 | 7002412000000000000♠412 kvadratkilometer
(70031067000000000000000♠1,067 km2 ) | 
|
| Codington County | 029 | Watertown | 1877 | Indianska marker | Pastor G.S. Codington, territoriell lagstiftare | 7004272270000000000♠27,227 | 70026880000000000000000♠688 kvadratkilometer
(70031782000000000000000♠1,782 km2 ) | 
|
| Corson County | 031 | McIntosh | 1909 | Indianska marker | Dighton Corson, domare i South Dakota Supreme Court | 7003405000000000000♠4,050 | 70032473000000000000000♠2,473 sq mi
(70036405000000000000000♠6,405 km2 ) | 
|
| Custer County | 033 | Custer | 1875 | Indianska marker | General George Armstrong Custer (1839 - 1876), nyckelperson i indiankrigen. | 7003821600000000000♠8,216 | 70031558000000000000000♠1,558 sq mi
(70034035000000000000000♠4,035 km2 ) | 
|
| Davison County | 035 | Mitchell | 1873 | Hanson | Henry C. Davison, framstående köpman och tidig bosättare. | 7004195040000000000♠19,504 | 7002436000000000000♠436 kvadratkilometer
(70031129000000000000000♠1,129 km2 ) | 
|
| Day County | 037 | Webster | 1879 | Clark | Merrit H. Day, territoriell lagstiftare | 7003571000000000000♠5,710 | 70031029000000000000000♠1,029 sq mi
(70032665000000000000000♠2,665 km2 ) | 
|
| Deuel County | 039 | Clear Lake | 1862 | Brookings | Jacob S. Deuel, territoriell lagstiftare | 7003436400000000000♠4,364 | 7002624000000000000♠624 kvadratkilometer
(7003161616000000000000000♠1,616 km2 ) | 
|
| Dewey County | 041 | Timber Lake | 1873 | Armstrong County och indianska marker | William P. Dewey, territoriell generalinspektör | 7003530100000000000♠5,301 | 70032303000000000000000♠2,303 sq mi
(70035965000000000000000♠5,965 km2 ) | 
|
| Douglas County | 043 | Rustning | 1873 | Charles Mix | Stephen A. Douglas (1813 - 1861), amerikansk senator från Illinois och förespråkare av folklig suveränitet som en medelväg i slaveridebatten. | 7003300200000000000♠3,002 | 70024340000000000000000♠434 kvadratkilometer
(70031124000000000000000♠1 124 km2 ) | 
|
| Edmunds län | 045 | Ipswich | 1873 | Buffalo | Newton Edmunds, guvernör för Dakota Territory | 7003407100000000000♠4,071 | 70031146000000000000000♠1,146 sq mi
(70032968000000000000000♠2,968 km2 ) | 
|
| Fall River County | 047 | Varma källor | 1883 | Custer | Fall River | 7003709400000000000♠7,094 | 70031740000000000000000♠1,740 sq mi
(70034507000000000000000♠4,507 km2 ) | 
|
| Faulk County | 049 | Faulkton | 1873 | Oorganiserad mark | Andrew Jackson Faulk, guvernör för Dakota Territory | 7003236400000000000♠2,364 | 70031000000000000000000♠1,000 sq mi
(70032590000000000000000♠2,590 km2 ) | 
|
| Grant County | 051 | Milbank | 1873 | Codington och Deuel län | Ulysses S. Grant (1822 - 1885), amerikansk president och general från inbördeskriget. | 7003735600000000000♠7,356 | 70026820000000000000000♠682 kvadratkilometer
(700317666600000000000♠1,766 km2 ) | 
|
| Gregory County | 053 | Burke | 1862 | Oorganiserat territorium | John Shaw Gregory, territoriell lagstiftare | 7003427100000000000♠4,271 | 70031016000000000000000♠1,016 kvadratkilometer
(70032631000000000000000♠2,631 km2 ) | 
|
| Håkon län | 055 | Philip | 1914 | Stanley County | Kung Haakon VII av Norge | 7003193700000000000♠1,937 | 70031813000000000000000♠1,813 sq mi
(70034696000000000000000♠4,696 km2 ) | 
|
| Hamlin County | 057 | Hayti | 1873 | Deuel County | Hannibal Hamlin, vicepresident och amerikansk senator från Maine | 7003590300000000000♠5,903 | 7002511000000000000♠511 kvadratkilometer
(70031323000000000000000♠1,323 km2 ) | 
|
| Hand County | 059 | Miller | 1873 | Buffalo County | George H. Hand, territoriell lagstiftare | 7003343100000000000♠3,431 | 70031437000000000000000♠1,437 km2
(70033722000000000000000♠3,722 km2 ) | 
|
| Hanson County | 061 | Alexandria | 1873 | Buffalo och Deuel län | Joseph R. Hanson, major i armén under indiankrigen och tidig bosättare. | 7003333100000000000♠3,331 | 7002435000000000000♠435 kvadratkilometer
(70031127000000000000000♠1,127 km2 ) | 
|
| Harding County | 063 | Buffalo | 1909 | Oorganiserad mark | J.A. Harding, talman i Dakota Territory | 7003125500000000000♠1,255 | 70032671000000000000000♠2,671 sq mi
(70036918000000000000000♠6,918 km2 ) | 
|
| Hughes län | 065 | Pierre | 1880 | Buffalo County | Alexander Hughes, territoriell lagstiftare | 7004170220000000000♠17,022 | 7002741000000000000♠741 kvadratkilometer
(70031919000000000000000♠1,919 km2 ) | 
|
| Hutchinson County | 067 | Olivet | 1862 | Oorganiserat territorium | John Hutchinson, territoriell lagstiftare | 7003734300000000000♠7,343 | 70028130000000000000000♠813 kvadratkilometer
(70032106000000000000000♠2,106 km2 ) | 
|
| Hyde County | 069 | Highmore | 1873 | Buffalo County | James Hyde, territoriell lagstiftare | 7003142000000000000♠1,420 | 70028610000000000000000♠861 kvadratkilometer
(70032230000000000000000♠2 230 km2 ) | 
|
| Jackson County | 071 | Kadoka | 1914 | Stanley County | J.R. Jackson, territoriell lagstiftare | 7003303100000000000♠3,031 | 70031869000000000000000♠1,869 sq mi
(70034841000000000000000♠4,841 km2 ) | 
|
| Jerauld County | 073 | Wessington Springs | 1883 | Aurora län | H.A. Jerauld, territoriell lagstiftare | 7003207000000000000♠2,070 | 7002530000000000000♠530 kvadratkilometer
(70031373000000000000000♠1,373 km2 ) | 
|
| Jones County | 075 | Murdo | 1916 | Lyman County | George W. Jones, territoriell lagstiftare | 7003100600000000000♠1,006 | 70029710000000000000000♠971 kvadratkilometer
(70032515000000000000000♠2,515 km2 ) | 
|
| Kingsbury County | 077 | De Smet | 1873 | Hanson County | George W. Kingsbury och T.A. Kingsbury, bröder och territoriella lagstiftare | 7003514800000000000♠5,148 | 70028380000000000000000♠838 kvadratkilometer
(70032170000000000000000♠2,170 km2 ) | 
|
| Lake County | 079 | Madison | 1873 | Brookings och Hanson län | Sjöar i länet | 7004112000000000000♠11,200 | 7002563000000000000♠563 kvadratkilometer
(70031458000000000000000♠1,458 km2 ) | 
|
| Lawrence County | 081 | Deadwood | 1875 | Oorganiserat territorium | John Lawrence (1839 - 1889), territoriell lagstiftare | 7004240970000000000♠24,097 | 70028000000000000000000♠800 kvadratkilometer
(7003207200200000000000♠2,072 km2 ) | 
|
| Lincoln County | 083 | Canton | 1867 | Oorganiserat territorium | Lincoln County, Maine | 7004448280000000000♠44,828 | 7002578000000000000♠578 kvadratkilometer
(70031497000000000000000♠1,497 km2 ) | 
|
| Lyman County | 085 | Kennebec | 1873 | Oorganiserat territorium | W.P. Lyman, territoriell lagstiftare | 7003375500000000000♠3,755 | 7003164000000000000♠1,640 sq mi
(70034248000000000000000♠4,248 km2 ) | 
|
| Marshall County | 091 | Britton | 1885 | Day County | Marshall Vincent, kommissionsledamot i Day County | 7003465600000000000♠4,656 | 70028390000000000000000♠839 kvadratkilometer
(70032173000000000000000♠2,173 km2 ) | 
|
| McCook County | 087 | Salem | 1873 | Hanson County | Edwin McCook, sekreterare i Dakota Territory | 7003561800000000000♠5,618 | 7002575000000000000♠575 kvadratkilometer
(70031489000000000000000♠1,489 km2 ) | 
|
| McPherson County | 089 | Leola | 1873 | Buffalo County | James B. McPherson (1828 - 1864), general från inbördeskriget | 7003245900000000000♠2,459 | 70031137000000000000000♠1,137 sq mi
(70032945000000000000000♠2,945 km2 ) | 
|
| Meade County | 093 | Sturgis | 1889 | Lawrence County | George G. Meade (1815 - 1872), general från inbördeskriget | 7004254340000000000♠25,434 | 70033471000000000000000♠3,471 kvadratkilometer
(70038990000000000000000♠8,990 km2 ) | 
|
| Mellette län | 095 | White River | 1909 | Lyman County | Arthur C. Mellette, South Dakotas första guvernör | 7003204800000000000♠2,048 | 70031307000000000000000♠1,307 sq mi
(70033385000000000000000♠3,385 km2 ) | 
|
| Miner County | 097 | Howard | 1873 | Hanson County | Nelson Miner och Ephriam Miner, bröder och territoriella lagstiftare | 7003238900000000000♠2,389 | 7002570000000000000♠570 kvadratkilometer
(70031476000000000000000♠1,476 km2 ) | 
|
| Minnehaha County | 099 | Sioux Falls | 1862 | Oorganiserat territorium | Sioux-uttryck för vattenfall | 7005169468000000000♠169,468 | 7002809000000000000♠809 kvadratkilometer
(70032095000000000000000♠2,095 km2 ) | 
|
| Moody County | 101 | Flandreau | 1873 | Brookings och Minnehaha län | Gideon C. Moody, talman i Dakota Territory | 7003648600000000000♠6,486 | 7002520000000000000♠520 kvadratkilometer
(70031347000000000000000♠1,347 km2 ) | 
|
| Oglala Lakota län | 102 | Varma källor | 1875 | Fall River County | Oglala Lakota-stammen | 7004135860000000000♠13,586 | 70032094000000000000000♠2,094 km2
(70035423000000000000000♠5,423 km2 ) | 
|
| Pennington County | 103 | Rapid City | 1875 | Oorganiserat territorium | John L. Pennington (1821-1900), guvernör i Dakota Territory | 7005100948000000000♠100,948 | 70032776000000000000000♠2,776 kvadratkilometer
(70037190000000000000000♠7,190 km2 ) | 
|
| Perkins län | 105 | Bison | 1909 | Butte och Harding län | Henry E. Perkins, senator i delstaten | 7003298200000000000♠2,982 | 7003287200000000000♠2,872 sq mi
(70037438000000000000000♠7,438 km2 ) | 
|
| Potter County | 107 | Gettysburg | 1875 | Buffalo County | Joel A. Potter, territoriell lagstiftare | 7003232900000000000♠2,329 | 70028660000000000000000♠866 kvadratkilometer
(70032243000000000000000♠2,243 km2 ) | 
|
| Roberts County | 109 | Sisseton | 1883 | Grant County | S.G. Roberts, territoriell lagstiftare | 7004101490000000000♠10,149 | 70031101000000000000000♠1,101 sq mi
(7003285200000000000♠2,852 km2 ) | 
|
| Sanborn County | 111 | Woonsocket | 1883 | Miner County | George W. Sanborn, ordförande för Milwaukee Railroad | 7003235500000000000♠2,355 | 70025690000000000000000♠569 kvadratkilometer
(70031474000000000000000♠1,474 km2 ) | 
|
| Spink County | 115 | Redfield | 1873 | Hanson County | S.L. Spink, sekreterare i Dakota Territory | 7003645100000000000♠6,451 | 70031504000000000000000♠1,504 sq mi
(70033895000000000000000♠3,895 km2 ) | 
|
| Stanley County | 117 | Fort Pierre | 1873 | Oorganiserat territorium | David S. Stanley, befälhavare för Fort Sully | 7003296600000000000♠2,966 | 70031443000000000000000♠1,443 sq mi
(70033737000000000000000♠3,737 km2 ) | 
|
| Sully län | 119 | Onida | 1873 | Potter County | Fort Sully, som i sin tur är uppkallat efter general Alfred Sully. | 7003137300000000000♠1,373 | 70031007000000000000000♠1,007 sq mi
(70032608000000000000000♠2,608 km2 ) | 
|
| Todd County | 121 | Vinnare | 1909 | Meyer och Tripp län | John Blair Smith Todd, territoriell delegat till kongressen | 7003961200000000000♠9,612 | 70031388000000000000000♠1,388 sq mi
(70033595000000000000000♠3,595 km2 ) | 
|
| Tripp County | 123 | Vinnare | 1873 | Oorganiserat territorium | Bartlett Tripp, överdomare i Dakota Territorial Supreme Court | 7003564400000000000♠5,644 | 70031614000000000000000♠1,614 sq mi
(70034180000000000000000♠4,180 km2 ) | 
|
| Turner County | 125 | Parker | 1871 | Lincoln County | John W. Turner, territoriell lagstiftare | 7003834700000000000♠8,347 | 7002617000000000000♠617 kvadratkilometer
(70031598000000000000000♠1,598 km2 ) | 
|
| Union County | 127 | Älgspetsen | 1862 | Oorganiserat territorium | De amerikanska staternas union | 7004143990000000000♠14,399 | 7002460000000000000♠460 kvadratkilometer
(7003119100000000000♠1,191 km2 ) | 
|
| Walworth County | 129 | Selby | 1873 | Buffalo County | Walworth County, Wisconsin | 7003543800000000000♠5,438 | 7002708000000000000♠708 kvadratkilometer
(70031834000000000000000♠1,834 km2 ) | 
|
| Yankton län | 135 | Yankton | 1862 | Oorganiserat territorium | Yankton Sioux indianer | 7004224380000000000♠22,438 | 70025220000000000000000♠522 kvadratkilometer
(7003135200200000000000♠1 352 km2 ) | 
|
| Ziebach län | 137 | Dupree | 1911 | Armstrong, Schnasse och Sterling län | Frank M. Ziebach, förläggare och major i armén under indiankriget. | 7003280100000000000♠2,801 | 7003196200000000000♠1,962 sq mi
(7003508200000000000♠5,082 km2 ) | 
|
