Wisconsin was admitted to the Union on May 29, 1848. Its current U.S. senators are Republican Ron Johnson (since 2011) and Democrat Tammy Baldwin (since 2013), making it one of three states to have a split United States Senate delegation . William Proxmire was the state's longest serving senator (served 1957âÂÂ1989).
|- style="height:2em" | colspan=3 | Vacant | nowrap | May 29, 1848 âÂÂ<br/>Jun 8, 1848 | Wisconsin elected its senators 10 days after statehood. | rowspan=3 | 1 | rowspan=2 | rowspan=2 | 1 | Wisconsin elected its senators 10 days after statehood. | nowrap | May 29, 1848 âÂÂ<br/>Jun 8, 1848 | colspan=3 | Vacant
|- style="height:2em" ! rowspan=5 | 1 | rowspan=5 align=left | <br/>Henry Dodge | rowspan=5 | Democratic | rowspan=5 nowrap | Jun 8, 1848 âÂÂ<br/>Mar 3, 1857 | rowspan=2 | Elected in 1848. | Elected in 1848. | rowspan=4 nowrap | Jun 8, 1848 âÂÂ<br/>Mar 3, 1855 | rowspan=4 | Democratic | rowspan=4 align=right | <br/>Isaac P. Walker ! rowspan=4 | 1
|- style="height:2em" | | rowspan=3 | 2 | rowspan=3 | Re-elected in 1849.Retired.
|- style="height:2em" | rowspan=3 | Re-elected in 1851.Retired. | rowspan=3 | 2 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 3 | rowspan=3 | Elected in 1855.<br/>Retired. | rowspan=3 nowrap | Mar 4, 1855 âÂÂ<br/>Mar 3, 1861 | rowspan=3 | Republican | rowspan=3 align=right | <br/>Charles Durkee ! rowspan=3 | 2
|- style="height:2em" ! rowspan=6 | 2 | rowspan=6 align=left | <br/>James R. Doolittle | rowspan=6 | Republican | rowspan=6 nowrap | Mar 4, 1857 âÂÂ<br/>Mar 3, 1869 | rowspan=3 | Elected in 1857. | rowspan=3 | 3 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 4 | rowspan=3 | Elected in 1861. | rowspan=9 nowrap | Mar 4, 1861 âÂÂ<br/>Mar 3, 1879 | rowspan=9 | Republican | rowspan=9 align=right | <br/>Timothy O. Howe ! rowspan=9 | 3
|- style="height:2em" | rowspan=3 | Re-elected in 1863.<br/>Retired. | rowspan=3 | 4 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 5 | rowspan=3 | Re-elected in 1867.
|- style="height:2em" ! rowspan=3 | 3 | rowspan=3 align=left | <br/>Matthew H. Carpenter | rowspan=3 | Republican | rowspan=3 nowrap | Mar 4, 1869 âÂÂ<br/>Mar 3, 1875 | rowspan=3 | Elected in 1869.Lost re-election. | rowspan=3 | 5 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 6 | rowspan=3 | Re-elected in 1872.Lost re-election.
|- style="height:2em" ! rowspan=4 | 4 | rowspan=4 align=left | <br/>Angus Cameron | rowspan=4 | Republican | rowspan=4 nowrap | Mar 4, 1875 âÂÂ<br/>Mar 3, 1881 | rowspan=4 | Elected in 1875.Retired. | rowspan=4 | 6 |
|- style="height:2em" |
|- style="height:2em" | rowspan=2 | rowspan=5 | 7 | Elected in 1879.Died. | nowrap | Mar 4, 1879 âÂÂ<br/>Feb 24, 1881 | | Republican | align=right | <br/>Matthew H. Carpenter ! 4
|- style="height:2em" | rowspan=2 | | rowspan=2 nowrap | Feb 24, 1881 âÂÂ<br/>Mar 14, 1881 | rowspan=2 colspan=3 | Vacant
|- style="height:2em" ! rowspan=7 | 5 | rowspan=7 align=left | <br/>Philetus Sawyer | rowspan=7 | Republican | rowspan=7 nowrap | Mar 4, 1881 âÂÂ<br/>Mar 3, 1893 | rowspan=4 | Elected in 1881. | rowspan=4 | 7 | rowspan=2
|- style="height:2em" | rowspan=2 | Elected to finish Carpenter's term.Retired. | rowspan=2 nowrap | Mar 14, 1881 âÂÂ<br/>Mar 3, 1885 | rowspan=2 | Republican | rowspan=2 align=right | <br/>Angus Cameron ! rowspan=2 | 5
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 8 | rowspan=3 | Elected in 1885.Lost re-election. | rowspan=3 nowrap | Mar 4, 1885 âÂÂ<br/>Mar 3, 1891 | rowspan=3 | Republican | rowspan=3 align=right | <br/>John Coit Spooner ! rowspan=3 | 6
|- style="height:2em" | rowspan=3 | Re-elected in 1887.Retired. | rowspan=3 | 8 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 9 | rowspan=3 | Elected in 1891.Lost renomination. | rowspan=3 nowrap | Mar 4, 1891 âÂÂ<br/>Mar 3, 1897 | rowspan=3 | Democratic | rowspan=3 align=right | <br/>William F. Vilas ! rowspan=3 | 7
|- style="height:2em" ! rowspan=3 | 6 | rowspan=3 align=left | <br/>John L. Mitchell | rowspan=3 | Democratic | rowspan=3 nowrap | Mar 4, 1893 âÂÂ<br/>Mar 3, 1899 | rowspan=3 | Elected in 1893.Retired. | rowspan=3 | 9 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 10 | rowspan=3 | Elected in 1897. | rowspan=6 nowrap | Mar 4, 1897 âÂÂ<br/>Apr 30, 1907 | rowspan=6 | Republican | rowspan=6 align=right | <br/>John Coit Spooner ! rowspan=6 | 8
|- style="height:2em" ! rowspan=3 | 7 | rowspan=3 align=left | <br/>Joseph V. Quarles | rowspan=3 | Republican | rowspan=3 nowrap | Mar 4, 1899 âÂÂ<br/>Mar 3, 1905 | rowspan=3 | Elected in 1899.Retired. | rowspan=3 | 10 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=5 | 11 | rowspan=3 | Re-elected in 1903.Resigned.
|- style="height:2em" ! rowspan=15 | 8 | rowspan=15 align=left | <br/>Robert M. La Follette | rowspan=15 | Republican | rowspan=15 nowrap | Jan 4, 1906 âÂÂ<br/>Jun 18, 1925 | rowspan=5 | Elected in 1905.Did not assume office until Jan 4, 1906 after resigning as Governor of Wisconsin. | rowspan=5 | 11 |
|- style="height:2em" | rowspan=3
|- style="height:2em" | | nowrap | Apr 30, 1907 âÂÂ<br/>May 17, 1907 | colspan=3 | Vacant
|- style="height:2em" | Elected to finish Spooner's term. | rowspan=4 nowrap | May 17, 1907 âÂÂ<br/>Mar 3, 1915 | rowspan=4 | Republican | rowspan=4 align=right | <br/>Isaac Stephenson ! rowspan=4 | 9
|- style="height:2em" | | rowspan=3 | 12 | rowspan=3 | Re-elected in 1909.Retired.
|- style="height:2em" | rowspan=3 | Re-elected in 1911. | rowspan=3 | 12 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=5 | 13 | rowspan=2 | Elected in 1914.Died. | rowspan=2 nowrap | Mar 4, 1915 âÂÂ<br/>Oct 21, 1917 | rowspan=2 | Democratic | rowspan=2 align=right | <br/>Paul O. Husting ! rowspan=2 | 10
|- style="height:2em" | rowspan=5 | Re-elected in 1916. | rowspan=5 | 13 | rowspan=3
|- style="height:2em" | | nowrap | Oct 21, 1917 âÂÂ<br/>Apr 18, 1918 | colspan=3 | Vacant
|- style="height:2em" | rowspan=2 | Elected in 1918 to finish Husting's term. | rowspan=7 nowrap | Apr 18, 1918 âÂÂ<br/>Mar 3, 1927 | rowspan=7 | Republican | rowspan=7 align=right | <br/>Irvine Lenroot ! rowspan=7 | 11
|- style="height:2em" |
|- style="height:2em" | | rowspan=5 | 14 | rowspan=5 | Re-elected in 1920.Lost renomination.
|- style="height:2em" | rowspan=2 | Re-elected in 1922.Died. | rowspan=5 | 14 |
|- style="height:2em" | rowspan=3
|- style="height:2em" | colspan=3 | Vacant | nowrap | Jun 18, 1925 âÂÂ<br/>Sep 30, 1925 |
|- style="height:2em" ! rowspan=11 | 9 | rowspan=11 align=left | <br/>Robert M. La Follette Jr. | rowspan=5 | Republican | rowspan=11 nowrap | Sep 30, 1925 âÂÂ<br/>Jan 3, 1947 | rowspan=2 | Elected to finish his father's term
|- style="height:2em" | | rowspan=3 | 15 | rowspan=3 | Elected in 1926.Lost renomination. | rowspan=3 nowrap | Mar 4, 1927 âÂÂ<br/>Mar 3, 1933 | rowspan=3 | Republican | rowspan=3 align=right | <br/>John J. Blaine ! rowspan=3 | 12
|- style="height:2em" | rowspan=3 | Re-elected in 1928. | rowspan=3 | 15 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 16 | rowspan=3 | Elected in 1932.Lost re-election. | rowspan=3 nowrap | Mar 4, 1933 âÂÂ<br/>Jan 3, 1939 | rowspan=3 | Democratic | rowspan=3 align=right | <br/>F. Ryan Duffy ! rowspan=3 | 13
|- style="height:2em" | rowspan=6 | Progressive | rowspan=3 | Re-elected in 1934. | rowspan=3 | 16 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 17 | rowspan=3 | Elected in 1938. | rowspan=14 nowrap | Jan 3, 1939 âÂÂ<br/>Jan 3, 1963 | rowspan=14 | Republican | rowspan=14 align=right | <br/>Alexander Wiley ! rowspan=14 | 14
|- style="height:2em" | rowspan=3 | Re-elected in 1940.Lost nomination as a Republican. | rowspan=3 | 17 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 18 | rowspan=3 | Re-elected in 1944.
|- style="height:2em" ! rowspan=6 | 10 | rowspan=6 align=left | <br/>Joseph McCarthy | rowspan=6 | Republican | rowspan=6 nowrap | Jan 3, 1947 âÂÂ<br/>May 2, 1957 | rowspan=3 | Elected in 1946. | rowspan=3 | 18 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 19 | rowspan=3 | Re-elected in 1950.
|- style="height:2em" | rowspan=3 | Re-elected in 1952.Died. | rowspan=5 | 19 |
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | rowspan=5 | 20 | rowspan=5 | Re-elected in 1956.Lost re-election.
|- style="height:2em" | colspan=3 | Vacant | nowrap | May 2, 1957 âÂÂ<br/>Aug 27, 1957 |
|- style="height:2em" ! rowspan=16 | 11 | rowspan=16 align=left | <br/>William Proxmire | rowspan=16 | Democratic | rowspan=16 nowrap | Aug 28, 1957 âÂÂ<br/>Jan 3, 1989 | Elected to finish McCarthy's term
|- style="height:2em" | rowspan=3 | Re-elected in 1958. | rowspan=3 | 20 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 21 | rowspan=3 | Elected in 1962. | rowspan=9 nowrap | Jan 3, 1963 âÂÂ<br/>Jan 3, 1981 | rowspan=9 | Democratic | rowspan=9 align=right | <br/>Gaylord Nelson ! rowspan=9 | 15
|- style="height:2em" | rowspan=3 | Re-elected in 1964. | rowspan=3 | 21 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 22 | rowspan=3 | Re-elected in 1968.
|- style="height:2em" | rowspan=3 | Re-elected in 1970. | rowspan=3 | 22 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 23 | rowspan=3 | Re-elected in 1974.Lost re-election.
|- style="height:2em" | rowspan=3 | Re-elected in 1976. | rowspan=3 | 23 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 24 | rowspan=3 | Elected in 1980. | rowspan=6 nowrap | Jan 3, 1981 âÂÂ<br/>Jan 3, 1993 | rowspan=6 | Republican | rowspan=6 align=right | <br/>Bob Kasten ! rowspan=6 | 16
|- style="height:2em" | rowspan=3 | Re-elected in 1982.Retired. | rowspan=3 | 24 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 25 | rowspan=3 | Re-elected in 1986.Lost re-election.
|- style="height:2em" ! rowspan=12 | 12 | rowspan=12 align=left | <br/>Herb Kohl | rowspan=12 | Democratic | rowspan=12 nowrap | Jan 3, 1989 âÂÂ<br/>Jan 3, 2013 | rowspan=3 | Elected in 1988. | rowspan=3 | 25 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 26 | rowspan=3 | Elected in 1992. | rowspan=9 nowrap | Jan 3, 1993 âÂÂ<br/>Jan 3, 2011 | rowspan=9 | Democratic | rowspan=9 align=right | <br/>Russ Feingold ! rowspan=9 | 17
|- style="height:2em" | rowspan=3 | Re-elected in 1994. | rowspan=3 | 26 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 27 | rowspan=3 | Re-elected in 1998.
|- style="height:2em" | rowspan=3 | Re-elected in 2000. | rowspan=3 | 27 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 28 | rowspan=3 | Re-elected in 2004.Lost re-election.
|- style="height:2em" | rowspan=3 | Re-elected in 2006.Retired. | rowspan=3 | 28 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 29 | rowspan=3 | Elected in 2010. | rowspan=9 nowrap | Jan 3, 2011 âÂÂ<br/>present | rowspan=9 | Republican | rowspan=9 align=right | <br/>Ron Johnson ! rowspan=9 | 18
|- style="height:2em" ! rowspan=9 | 13 | rowspan=9 align=left | <br/>Tammy Baldwin | rowspan=9 | Democratic | rowspan=9 nowrap | Jan 3, 2013 âÂÂ<br/>present | rowspan=3 | Elected in 2012. | rowspan=3 | 29 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 30 | rowspan=3 | Re-elected in 2016.
|- style="height:2em" | rowspan=3 | Re-elected in 2018. | rowspan=3 | 30 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=3 | 31 | rowspan=3 | Re-elected in 2022.
|- style="height:2em" | rowspan=3 | Re-elected in 2024. | rowspan=3 | 31 |
|- style="height:2em" |
|- style="height:2em" | | rowspan=2 | 32 | rowspan=2 colspan=5 | To be determined in the 2028 election.
|- style="height:2em" | colspan=5 | To be determined in the 2030 election. | 32 |