South Dakota was admitted to the Union on November 2, 1889, and elects U.S. senators to class 2 and class 3. Its current U.S. senators are Republicans John Thune (since 2005) and Mike Rounds (since 2015). Karl E. Mundt is South Dakota's longest-serving senator (1948âÂÂ1973). South Dakota is one of 15 states alongside California, Colorado, Georgia, Hawaii, Idaho, Louisiana, Maine, Massachusetts, Minnesota, Missouri, Nevada, Pennsylvania, and Utah to have a younger senior senator and an older junior senator. South Dakota's class 3 seat also holds the distinction of having a future Senate Majority Leader (John Thune) defeat and succeed a former Majority Leader (Tom Daschle).
|- style="height:2em" ! rowspan=6 | 1 | rowspan=6 align=left | <br/>Richard Pettigrew | rowspan=4 | Republican | rowspan=6 nowrap | Nov 2, 1889 âÂÂ<br/>Mar 3, 1901 | rowspan=3 | Elected in 1889. | rowspan=3 | 1 | | 1 | Elected in 1889.Lost re-election. | nowrap | Nov 2, 1889 âÂÂ<br/>Mar 3, 1891 | | Republican | align=right | <br/>Gideon C. Moody ! 1
|- style="height:2em" | | rowspan=3 | 2 | rowspan=3 | Elected in 1891.
| rowspan=6 nowrap | Mar 4, 1891 âÂÂ<br/>Jul 1, 1901 | | Independent | rowspan=6 align=right | <br/>James H. Kyle ! rowspan=6 | 2
|- style="height:2em" | | rowspan=4 | Populist
|- style="height:2em" | rowspan=3 | Re-elected in 1894.Lost re-election. | rowspan=3 | 2 |
|- style="height:2em" | rowspan=2 | Silver<br/>Republican | | rowspan=5 | 3 | rowspan=3 | Re-elected in 1897.Died.
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|- style="height:2em" ! rowspan=8 | 2 | rowspan=8 align=left | <br/> Robert J. Gamble | rowspan=8 | Republican | rowspan=8 nowrap | Mar 4, 1901 âÂÂ<br/>Mar 3, 1913 | rowspan=5 | Elected in 1901. | rowspan=5 | 3 | rowspan=3 | | Republican
|- style="height:2em" | | nowrap | Jul 1, 1901 âÂÂ<br/>Jul 11, 1901 | colspan=3 | Vacant
|- style="height:2em" | Appointed to continue Kyle's term.Elected in 1903 to finish Kyle's term. | rowspan=4 nowrap | Jul 11, 1901 âÂÂ<br/>Mar 3, 1909 | rowspan=4 | Republican | rowspan=4 align=right | <br/>Alfred B. Kittredge ! rowspan=4 | 3
|- style="height:2em" | | rowspan=3 | 4 | rowspan=3 | Elected to a full term in 1903.Lost renomination.
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|- style="height:2em" | rowspan=3 | Re-elected in 1907.Lost renomination. | rowspan=3 | 4 |
|- style="height:2em" | | rowspan=3 | 5 | rowspan=3 | Elected in 1909.Lost renomination. | rowspan=3 nowrap | Mar 4, 1909 âÂÂ<br/>Mar 3, 1915 | rowspan=3 | Republican | rowspan=3 align=right | <br/>Coe Crawford ! rowspan=3 | 4
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|- style="height:2em" ! rowspan=6 | 3 | rowspan=6 align=left | <br/>Thomas Sterling | rowspan=6 | Republican | rowspan=6 nowrap | Mar 4, 1913 âÂÂ<br/>Mar 3, 1925 | rowspan=3 | Elected in 1913. | rowspan=3 | 5 |
|- style="height:2em" | | rowspan=3 | 6 | rowspan=3 | Elected in 1914.Retired. | rowspan=3 nowrap | Mar 4, 1915 âÂÂ<br/>Mar 3, 1921 | rowspan=3 | Democratic | rowspan=3 align=right | <br/>Edwin S. Johnson ! rowspan=3 | 5
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|- style="height:2em" | rowspan=3 | Re-elected in 1918.Lost renomination. | rowspan=3 | 6 |
|- style="height:2em" | | rowspan=3 | 7 | rowspan=3 | Elected in 1920. | rowspan=8 nowrap | Mar 4, 1921 âÂÂ<br/>Dec 20, 1936 | rowspan=8 | Republican | rowspan=8 align=right | <br/>Peter Norbeck ! rowspan=8 | 6
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|- style="height:2em" ! rowspan=3 | 4 | rowspan=3 align=left | <br/>William McMaster | rowspan=3 | Republican | rowspan=3 nowrap | Mar 4, 1925 âÂÂ<br/>Mar 3, 1931 | rowspan=3 | Elected in 1924.Lost re-election. | rowspan=3 | 7 |
|- style="height:2em" | | rowspan=3 | 8 | rowspan=3 | Re-elected in 1926.
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|- style="height:2em" ! rowspan=9 | 5 | rowspan=9 align=left | <br/>William J. Bulow | rowspan=9 | Democratic | rowspan=9 nowrap | Mar 4, 1931 âÂÂ<br/>Jan 3, 1943 | rowspan=5 | Elected in 1930. | rowspan=5 | 8 |
|- style="height:2em" | | rowspan=6 | 9 | rowspan=2 | Re-elected in 1932.Died.
|- style="height:2em" | rowspan=3
|- style="height:2em" | | nowrap | Dec 20, 1936 âÂÂ<br/>Dec 29, 1936 | colspan=3 | Vacant
|- style="height:2em" | rowspan=2 | Appointed to continue Norbeck's term.Lost nomination to a full term. | rowspan=2 nowrap | Dec 29, 1936 âÂÂ<br/>Nov 8, 1938 | rowspan=2 | Democratic | rowspan=2 align=right | <br/>Herbert Hitchcock ! rowspan=2 | 7
|- style="height:2em" | rowspan=4 | Re-elected in 1936.Lost renomination. | rowspan=4 | 9 | rowspan=2
|- style="height:2em" | Elected to finish Norbeck's term.Retired. | nowrap | Nov 9, 1938 âÂÂ<br/>Jan 3, 1939 | | Republican | align=right | <br/>Gladys Pyle ! 8
|- style="height:2em" | | rowspan=3 | 10 | rowspan=3 | Elected in 1938. | rowspan=10 nowrap | Jan 3, 1939 âÂÂ<br/>Jan 3, 1951 | rowspan=10 | Republican | rowspan=10 align=right | <br/>Chan Gurney ! rowspan=10 | 9
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|- style="height:2em" ! rowspan=3 | 6 | rowspan=3 align=left | <br/>Harlan J. Bushfield | rowspan=3 | Republican | rowspan=3 nowrap | Jan 3, 1943 âÂÂ<br/>Sep 27, 1948 | rowspan=3 | Elected in 1942.Died. | rowspan=7 | 10 |
|- style="height:2em" | | rowspan=7 | 11 | rowspan=7 | Re-elected in 1944.Lost renomination.
|- style="height:2em" | rowspan=5
|- style="height:2em" | colspan=3 | Vacant | nowrap | Sep 27, 1948 âÂÂ<br/>Oct 6, 1948 |
|- style="height:2em" ! 7 | align=left | <br/>Vera C. Bushfield | | Republican | nowrap | Oct 6, 1948 âÂÂ<br/>Dec 26, 1948 | Appointed to finish her husband's term.Resigned when successor appointed.
|- style="height:2em" | colspan=3 | Vacant | nowrap | Dec 26, 1948 âÂÂ<br/>Dec 31, 1948 |
|- style="height:2em" ! rowspan=15 | 8 | rowspan=15 align=left | <br/>Karl Mundt | rowspan=15 | Republican | rowspan=15 nowrap | Dec 31, 1948 âÂÂ<br/>Jan 3, 1973 | Appointed to finish Bushfield's term, having been elected to the next term.
|- style="height:2em" | rowspan=3 | Elected in 1948 | rowspan=3 | 11 |
|- style="height:2em" | | rowspan=3 | 12 | rowspan=3 | Elected in 1950. | rowspan=6 nowrap | Jan 3, 1951 âÂÂ<br/>Jun 22, 1962 | rowspan=6 | Republican | rowspan=6 align=right | <br/>Francis Case ! rowspan=6 | 10
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1954. | rowspan=3 | 12 |
|- style="height:2em" | | rowspan=5 | 13 | rowspan=3 | Re-elected in 1956.Died.
|- style="height:2em" |
|- style="height:2em" | rowspan=5 | Re-elected in 1960. | rowspan=5 | 13 | rowspan=3
|- style="height:2em" | | nowrap | Jun 22, 1962 âÂÂ<br/>Jul 9, 1962 | colspan=3 | Vacant
|- style="height:2em" | Appointed to finish Case's term.Lost election to full term. | nowrap | Jul 9, 1962 âÂÂ<br/>Jan 3, 1963 | | Republican | align=right | <br/>Joe Bottum ! 11
|- style="height:2em" | | rowspan=3 | 14 | rowspan=3 | Elected in 1962. | rowspan=9 nowrap | Jan 3, 1963 âÂÂ<br/>Jan 3, 1981 | rowspan=9 | Democratic | rowspan=9 align=right | <br/>George McGovern ! rowspan=9 | 12
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1966.Retired. | rowspan=3 | 14 |
|- style="height:2em" | | rowspan=3 | 15 | rowspan=3 | Re-elected in 1968.
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|- style="height:2em" ! rowspan=3 | 9 | rowspan=3 align=left | <br/>James Abourezk | rowspan=3 | Democratic | rowspan=3 nowrap | Jan 3, 1973 âÂÂ<br/>Jan 3, 1979 | rowspan=3 | Elected in 1972.Retired. | rowspan=3 | 15 |
|- style="height:2em" | | rowspan=3 | 16 | rowspan=3 | Re-elected in 1974.Lost re-election.
|- style="height:2em" |
|- style="height:2em" ! rowspan=9 | 10 | rowspan=9 align=left | <br/>Larry Pressler | rowspan=9 | Republican | rowspan=9 nowrap | Jan 3, 1979 âÂÂ<br/>Jan 3, 1997 | rowspan=3 | Elected in 1978. | rowspan=3 | 16 |
|- style="height:2em" | | rowspan=3 | 17 | rowspan=3 | Elected in 1980.Lost re-election. | rowspan=3 nowrap | Jan 3, 1981 âÂÂ<br/>Jan 3, 1987 | rowspan=3 | Republican | rowspan=3 align=right | <br/>James Abdnor ! rowspan=3 | 13
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1984. | rowspan=3 | 17 |
|- style="height:2em" | | rowspan=3 | 18 | rowspan=3 | Elected in 1986. | rowspan=9 nowrap | Jan 3, 1987 âÂÂ<br/>Jan 3, 2005 | rowspan=9 | Democratic | rowspan=9 align=right | <br/>Tom Daschle ! rowspan=9 | 14
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1990.Lost re-election. | rowspan=3 | 18 |
|- style="height:2em" | | rowspan=3 | 19 | rowspan=3 | Re-elected in 1992.
|- style="height:2em" |
|- style="height:2em" ! rowspan=9 | 11 | rowspan=9 align=left | <br/>Tim Johnson | rowspan=9 | Democratic | rowspan=9 nowrap | Jan 3, 1997 âÂÂ<br/>Jan 3, 2015 | rowspan=3 | Elected in 1996. | rowspan=3 | 19 |
|- style="height:2em" | | rowspan=3 | 20 | rowspan=3 | Re-elected in 1998.Lost re-election.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 2002. | rowspan=3 | 20 |
|- style="height:2em" | | rowspan=3 | 21 | rowspan=3 | Elected in 2004. | rowspan=12 nowrap | Jan 3, 2005 âÂÂ<br/>present | rowspan=12 | Republican | rowspan=12 align=right | <br/>John Thune ! rowspan=12 | 15
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 2008.Retired. | rowspan=3 | 21 |
|- style="height:2em" | | rowspan=3 | 22 | rowspan=3 | Re-elected in 2010.
|- style="height:2em" |
|- style="height:2em" ! rowspan=6 | 12 | rowspan=6 align=left | <br/>Mike Rounds | rowspan=6 | Republican | rowspan=6 nowrap | Jan 3, 2015 âÂÂ<br/>present | rowspan=3 | Elected in 2014. | rowspan=3 | 22 |
|- style="height:2em" | | rowspan=3 | 23 | rowspan=3 | Re-elected in 2016.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 2020. | rowspan=3 | 23 |
|- style="height:2em" | | rowspan=3|24 | rowspan=3 | Re-elected in 2022.
|- style="height:2em" |
|- style="height:2em" | rowspan=2 colspan=5 | To be determined in the 2026 election. | rowspan=2| 24 |
|- style="height:2em" | | 25 | colspan=5 | To be determined in the 2028 election.