Maine was admitted to the Union on March 15, 1820. The state's U.S. senators belong to class 1 and class 2. Republican Susan Collins (first elected in 1996) and independent Angus King (first elected in 2012) are Maine's current U.S. senators, making Maine one of four states to have a split United States Senate delegation. William P. Frye was Maine's longest serving senator (1881âÂÂ1911). Maine is one of fourteen states alongside California, Colorado, Georgia, Hawaii, Idaho, Louisiana, Massachusetts, Minnesota, Missouri, Nevada, Pennsylvania, South Dakota, and Utah to have a younger senior senator and an older junior senator.
|- style="height:2em" ! rowspan=4 | 1 | rowspan=4 align=left | <br/>John Holmes<br /> | rowspan=3 | Democratic-<br/>Republican | nowrap rowspan=4 | Jun 13, 1820 âÂÂ<br/>Mar 3, 1827 | Elected in 1820. | 1 | | rowspan=2 | 1 | rowspan=2 | Elected in 1820. | nowrap rowspan=7 | Jun 14, 1820 âÂÂ<br/>Mar 3, 1829 | rowspan=3 | Democratic-<br/>Republican | rowspan=7 align=right | <br/>John Chandler<br /> ! rowspan=7 | 1
|- style="height:2em" | rowspan=3 | Re-elected in 1821. | rowspan=3 | 2 |
|- style="height:2em" | | rowspan=5 | 2 | rowspan=5 | Re-elected in 1823.Retired.
|- style="height:2em" | | National<br/>Republican | | rowspan=4 | Jacksonian
|- style="height:2em" ! 2 | align=left | <br/>Albion Parris<br /> | | Jacksonian | nowrap | Mar 4, 1827 âÂÂ<br/>Aug 26, 1828 | Elected in 1827.Resigned to become a judge on the Maine Supreme Judicial Court. | rowspan=5 | 3 | rowspan=3
|- style="height:2em" | colspan=3 | Vacant | nowrap | Aug 26, 1828 âÂÂ<br/>Jan 15, 1829 |
|- style="height:2em" ! rowspan=3 | 3 | rowspan=3 align=left | <br/>John Holmes<br /> | rowspan=3 | National<br/>Republican | nowrap rowspan=3 | Jan 15, 1829 âÂÂ<br/>Mar 3, 1833 | rowspan=3 | Elected to finish Parris's term.Retired.
|- style="height:2em" | | rowspan=5 | 3 | rowspan=3 | Elected in 1829.Resigned. | nowrap rowspan=3 | Mar 4, 1829 âÂÂ<br/>Jan 1, 1835 | rowspan=3 | National<br/>Republican | rowspan=3 align=right | <br/>Peleg Sprague<br /> ! rowspan=3 | 2
|- style="height:2em" |
|- style="height:2em" ! rowspan=4 | 4 | rowspan=4 align=left | <br/>Ether Shepley<br /> | rowspan=4 | Jacksonian | nowrap rowspan=4 | Mar 4, 1833 âÂÂ<br/>Mar 3, 1836 | rowspan=4 | Elected in 1833.Resigned to become Justice of the Maine Supreme Judicial Court. | rowspan=6 | 4 | rowspan=3
|- style="height:2em" | | nowrap | Jan 1, 1835 âÂÂ<br/>Jan 20, 1835 | colspan=3 | Vacant
|- style="height:2em" | Elected to finish Sprague's term, having already been elected to the next term. | nowrap rowspan=5 | Jan 20, 1835 âÂÂ<br/>Mar 3, 1841 | rowspan=3 | Jacksonian | rowspan=5 align=right | <br/>John Ruggles<br /> ! rowspan=5 | 3
|- style="height:2em" | rowspan=2 | rowspan=4 | 4 | rowspan=4 | Elected in 1835.Lost re-election.
|- style="height:2em" ! 5 | align=left | <br/>Judah Dana<br /> | | Jacksonian | nowrap | Mar 4, 1836 âÂÂ<br/>Mar 3, 1837 | Appointed to continue Shepley's term.Either lost election to finish the term or retired when elected successor qualified.
|- style="height:2em" ! rowspan=3 | 6 | rowspan=3 align=left | <br/>Reuel Williams<br /> | rowspan=3 | Democratic | nowrap rowspan=3 | Mar 4, 1837 âÂÂ<br/>Feb 15, 1843 | Elected to finish Shepley's term. | | rowspan=2 | Democratic
|- style="height:2em" | rowspan=2 | Re-elected in 1839.Resigned. | rowspan=5 | 5 |
|- style="height:2em" | rowspan=2 | rowspan=5 | 5 | rowspan=5 | Elected in 1840.Lost re-election. | nowrap rowspan=5 | Mar 4, 1841 âÂÂ<br/>Mar 3, 1847 | rowspan=5 | Whig | rowspan=5 align=right | <br/>George Evans<br /> ! rowspan=5 | 4
|- style="height:2em" | rowspan=2 colspan=3 | Vacant | nowrap rowspan=2 | Feb 15, 1843 âÂÂ<br/>Dec 4, 1843 | rowspan=2 |
|- style="height:2em" | rowspan=2
|- style="height:2em" ! rowspan=3 | 7 | rowspan=3 align=left | <br/>John Fairfield<br /> | rowspan=3 | Democratic | nowrap rowspan=3 | Dec 4, 1843 âÂÂ<br/>Dec 24, 1847 | Elected to finish Williams's term.
|- style="height:2em" | rowspan=2 | Re-elected in 1844 or 1845.Died. | rowspan=6 | 6 |
|- style="height:2em" | rowspan=4 | rowspan=6 | 6 | rowspan=6 | Elected in 1846.Retired. | nowrap rowspan=6 | Mar 4, 1847 âÂÂ<br/>Mar 3, 1853 | rowspan=6 | Democratic | rowspan=6 align=right | <br/>James W. Bradbury<br /> ! rowspan=6 | 5
|- style="height:2em" | colspan=3 | Vacant | nowrap | Dec 24, 1847 âÂÂ<br/>Jan 5, 1848 |
|- style="height:2em" ! 8 | align=left | <br/>Wyman B. S. Moor<br /> | | Democratic | nowrap | Jan 5, 1848 âÂÂ<br/>June 7, 1848 | Appointed to continue term.Successor elected.
|- style="height:2em" ! rowspan=7 | 9 | rowspan=7 align=left | <br/>Hannibal Hamlin<br /> | rowspan=6 | Democratic | nowrap rowspan=7 | Jun 8, 1848 âÂÂ<br/>Jan 7, 1857 | rowspan=2 | Elected in 1848 to finish term.
|- style="height:2em" |
|- style="height:2em" | rowspan=5 | Re-elected in 1851.Changed parties in 1856.Resigned to become Governor of Maine. | rowspan=7 | 7 |
|- style="height:2em" | rowspan=2 | rowspan=7 | 7 | Legislature failed to elect. | nowrap | Mar 4, 1853 âÂÂ<br/>Feb 10, 1854 | colspan=3 | Vacant
|- style="height:2em" | rowspan=6 | Elected to finish term. | nowrap rowspan=10 | Feb 10, 1854 âÂÂ<br/>Jul 1, 1864 | rowspan=5 | Whig | rowspan=10 align=right | <br/>William P. Fessenden<br /> ! rowspan=10 | 6
|- style="height:2em" | rowspan=4
|- style="height:2em" | | Republican
|- style="height:2em" | colspan=3 | Vacant | nowrap | Jan 7, 1857 âÂÂ<br/>Jan 16, 1857 |
|- style="height:2em" ! 10 | align=left | <br/>Amos Nourse<br /> | | Republican | nowrap | Jan 16, 1857 âÂÂ<br/>Mar 3, 1857 | Elected in 1857 to finish term.Retired.
|- style="height:2em" ! rowspan=2 | 11 | rowspan=2 align=left | <br/>Hannibal Hamlin<br /> | rowspan=2 | Republican | nowrap rowspan=2 | Mar 4, 1857 âÂÂ<br/>Jan 17, 1861 | rowspan=2 | Elected in 1857.Resigned to become Vice President of the United States. | rowspan=4 | 8 | | rowspan=5 | Republican
|- style="height:2em" | rowspan=2 | rowspan=6 | 8 | rowspan=4 | Re-elected in 1859.Resigned to become U.S. Secretary of the Treasury.
|- style="height:2em" ! rowspan=7 | 12 | rowspan=7 align=left | <br/>Lot M. Morrill<br /> | rowspan=7 | Republican | nowrap rowspan=7 | Jan 17, 1861 âÂÂ<br/>Mar 3, 1869 | rowspan=2 | Elected in 1861 to finish term.
|- style="height:2em" |
|- style="height:2em" | rowspan=5 | Re-elected in 1863.Lost re-election. | rowspan=5 | 9 | rowspan=3
|- style="height:2em" | | nowrap | Jul 1, 1864 âÂÂ<br/>Oct 27, 1864 | colspan=3 | Vacant
|- style="height:2em" | Appointed to continue Fessenden's term.Elected in 1865 to finish Fessenden's term.Retired. | nowrap | Oct 27, 1864 âÂÂ<br/>Mar 3, 1865 | | Republican | align=right | <br/>Nathan A. Farwell<br /> ! 7
|- style="height:2em" | | rowspan=5 | 9 | rowspan=3 | Elected in 1864 or 1865.Died. | nowrap rowspan=3 | Mar 4, 1865 âÂÂ<br/>Sep 8, 1869 | rowspan=3 | Republican | rowspan=3 align=right | <br/>William P. Fessenden<br /> ! rowspan=3 | 8
|- style="height:2em" |
|- style="height:2em" ! rowspan=10 | 13 | rowspan=10 align=left | <br/>Hannibal Hamlin<br /> | rowspan=10 | Republican | nowrap rowspan=10 | Mar 4, 1869 âÂÂ<br/>Mar 3, 1881 | rowspan=5 | Elected in 1869. | rowspan=5 | 10 | rowspan=3
|- style="height:2em" | | nowrap | Sep 8, 1869 âÂÂ<br/>Oct 30, 1869 | colspan=3 | Vacant
|- style="height:2em" | Appointed to finish Fessenden's term.Elected in 1870 to finish Fessenden's term. | nowrap rowspan=4 | Oct 30, 1869 âÂÂ<br/>Jul 7, 1876 | rowspan=4 | Republican | rowspan=4 align=right | <br/>Lot M. Morrill<br /> ! rowspan=4 | 9
|- style="height:2em" | | rowspan=5 | 10 | rowspan=3 | Re-election year unknown.Resigned to become U.S. Secretary of the Treasury.
|- style="height:2em" |
|- style="height:2em" | rowspan=5 | Re-elected in 1875.Retired. | rowspan=5 | 11 | rowspan=3
|- style="height:2em" | | nowrap | Jul 7, 1876 âÂÂ<br/>Jul 10, 1876 | colspan=3 | Vacant
|- style="height:2em" | Appointed to finish Morrill's term.Elected in 1877 to finish Morrill's term. | nowrap rowspan=4 | Jul 10, 1876 âÂÂ<br/>Mar 5, 1881 | rowspan=4 | Republican | rowspan=4 align=right | <br/>James G. Blaine<br /> ! rowspan=4 | 10
|- style="height:2em" | | rowspan=5 | 11 | rowspan=3 | Elected to full term in 1877.Resigned to become U.S. Secretary of State.
|- style="height:2em" |
|- style="height:2em" ! rowspan=17 | 14 | rowspan=17 align=left | <br/>Eugene Hale<br /> | rowspan=17 | Republican | nowrap rowspan=17 | Mar 4, 1881 âÂÂ<br/>Mar 3, 1911 | rowspan=5 | Elected in 1881. | rowspan=5 | 12 | rowspan=3
|- style="height:2em" | | nowrap | Mar 5, 1881 âÂÂ<br/>Mar 18, 1881 | colspan=3 | Vacant
|- style="height:2em" | Elected to finish Blaine's term | nowrap rowspan=16 | Mar 18, 1881 âÂÂ<br/>Aug 8, 1911 | rowspan=16 | Republican | rowspan=16 align=right | <br/>William P. Frye<br /> ! rowspan=16 | 11
|- style="height:2em" | | rowspan=3 | 12 | rowspan=3 | Re-elected in 1883.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1887. | rowspan=3 | 13 |
|- style="height:2em" | | rowspan=3 | 13 | rowspan=3 | Re-elected in 1889.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1893. | rowspan=3 | 14 |
|- style="height:2em" | | rowspan=3 | 14 | rowspan=3 | Re-elected in 1895.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1899. | rowspan=3 | 15 |
|- style="height:2em" | | rowspan=3 | 15 | rowspan=3 | Re-elected in 1901.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1905.Retired. | rowspan=3 | 16 |
|- style="height:2em" | | rowspan=5 | 16 | rowspan=3 | Re-elected in 1907.Died.
|- style="height:2em" |
|- style="height:2em" ! rowspan=7 | 15 | rowspan=7 align=left | <br/>Charles F. Johnson<br /> | rowspan=7 | Democratic | nowrap rowspan=7 | Mar 4, 1911 âÂÂ<br/>Mar 3, 1917 | rowspan=7 | Elected in 1911.Lost re-election. | rowspan=7 | 17 | rowspan=3
|- style="height:2em" | | nowrap | Aug 8, 1911 âÂÂ<br/>Sep 23, 1911 | colspan=3 | Vacant
|- style="height:2em" | Appointed to continue Frye's term.Elected in 1912 to finish Frye's term.Lost re-election. | nowrap | Sep 23, 1911 âÂÂ<br/>Mar 3, 1913 | | Democratic | align=right | <br/>Obadiah Gardner<br /> ! 12
|- style="height:2em" | | rowspan=5 | 17 | rowspan=2 | Elected in 1913.Died. | nowrap rowspan=2 | Mar 4, 1913 âÂÂ<br/>Jun 16, 1916 | rowspan=2 | Republican | rowspan=2 align=right | <br/>Edwin C. Burleigh<br /> ! rowspan=2 | 13
|- style="height:2em" | rowspan=3
|- style="height:2em" | | nowrap | Jun 16, 1916 âÂÂ<br/>Sep 12, 1916 | colspan=3 | Vacant
|- style="height:2em" | rowspan=2 | Elected to finish Burleigh's term. | nowrap rowspan=6 | Sep 12, 1916 âÂÂ<br/>Aug 23, 1926 | rowspan=6 | Republican | rowspan=6 align=right | <br/>Bert M. Fernald<br /> ! rowspan=6 | 14
|- style="height:2em" ! rowspan=14 | 16 | rowspan=14 align=left | <br/>Frederick Hale<br /> | rowspan=14 | Republican | nowrap rowspan=14 | Mar 4, 1917 âÂÂ<br/>Jan 3, 1941 | rowspan=3 | Elected in 1916. | rowspan=3 | 18 |
|- style="height:2em" | | rowspan=3 | 18 | rowspan=3 | Re-elected in 1918.
|- style="height:2em" |
|- style="height:2em" | rowspan=5 | Re-elected in 1922. | rowspan=5 | 19 |
|- style="height:2em" | rowspan=3 | rowspan=5 | 19 | Re-elected in 1924.Died.
|- style="height:2em" | | nowrap | Aug 23, 1926 âÂÂ<br/>Nov 30, 1926 | colspan=3 | Vacant
|- style="height:2em" | rowspan=3 | Elected to finish Fernald's term.Retired. | nowrap rowspan=3 | Nov 30, 1926 âÂÂ<br/>Mar 3, 1931 | rowspan=3 | Republican | rowspan=3 align=right | <br/>Arthur R. Gould<br /> ! rowspan=3 | 15
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1928. | rowspan=3 | 20 |
|- style="height:2em" | | rowspan=3 | 20 | rowspan=3 | Elected in 1930. | nowrap rowspan=9 | Mar 4, 1931 âÂÂ<br/>Jan 3, 1949 | rowspan=9 | Republican | rowspan=9 align=right | <br/>Wallace H. White<br /> ! rowspan=9 | 16
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1934.Retired. | rowspan=3 | 21 |
|- style="height:2em" | | rowspan=3 | 21 | rowspan=3 | Re-elected in 1936.
|- style="height:2em" |
|- style="height:2em" ! rowspan=6 | 17 | rowspan=6 align=left | <br/>Owen Brewster<br /> | rowspan=6 | Republican | nowrap rowspan=6 | Jan 3, 1941 âÂÂ<br/>Dec 31, 1952 | rowspan=3 | Elected in 1940. | rowspan=3 | 22 |
|- style="height:2em" | | rowspan=3 | 22 | rowspan=3 | Re-elected in 1942.Retired.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1946.Resigned, having already lost renomination. | rowspan=4 | 23 |
|- style="height:2em" | | rowspan=4 | 23 | rowspan=4 | Elected in 1948. | nowrap rowspan=13 | Jan 3, 1949 âÂÂ<br/>Jan 3, 1973 | rowspan=13 | Republican | rowspan=13 align=right | <br/>Margaret Chase Smith<br /> ! rowspan=13 | 17
|- style="height:2em" | rowspan=2
|- style="height:2em" | colspan=3 | Vacant | nowrap | Dec 31, 1952 âÂÂ<br/>Jan 3, 1953 |
|- style="height:2em" ! rowspan=3 | 18 | rowspan=3 align=left | <br/>Frederick G. Payne<br /> | rowspan=3 | Republican | nowrap rowspan=3 | Jan 3, 1953 âÂÂ<br/>Jan 3, 1959 | rowspan=3 | Elected in 1952.Lost re-election. | rowspan=3 | 24 |
|- style="height:2em" | | rowspan=3 | 24 | rowspan=3 | Re-elected in 1954.
|- style="height:2em" |
|- style="height:2em" ! rowspan=11 | 19 | rowspan=11 align=left | <br/>Edmund Muskie<br /> | rowspan=11 | Democratic | nowrap rowspan=11 | Jan 3, 1959 âÂÂ<br/>May 7, 1980 | rowspan=3 | Elected in 1958. | rowspan=3 | 25 |
|- style="height:2em" | | rowspan=3 | 25 | rowspan=3 | Re-elected in 1960.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1964. | rowspan=3 | 26 |
|- style="height:2em" | | rowspan=3 | 26 | rowspan=3 | Re-elected in 1966.Lost re-election.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1970. | rowspan=3 | 27 |
|- style="height:2em" | | rowspan=3 | 27 | rowspan=3 | Elected in 1972.Lost re-election. | nowrap rowspan=3 | Jan 3, 1973 âÂÂ<br/>Jan 3, 1979 | rowspan=3 | Democratic | rowspan=3 align=right | <br/>Bill Hathaway<br /> ! rowspan=3 | 18
|- style="height:2em" |
|- style="height:2em" | rowspan=2 | Re-elected in 1976.Resigned to become U.S. Secretary of State. | rowspan=5 | 28 |
|- style="height:2em" | rowspan=3 | rowspan=5 | 28 | rowspan=5 | Elected in 1978. | nowrap rowspan=11 | Jan 3, 1979 âÂÂ<br/>Jan 3, 1997 | rowspan=11 | Republican | rowspan=11 align=right | <br/>William Cohen<br /> ! rowspan=11 | 19
|- style="height:2em" | colspan=3 | Vacant | nowrap | May 7, 1980 âÂÂ<br/>May 19, 1980 |
|- style="height:2em" ! rowspan=8 | 20 | rowspan=8 align=left | <br/>George J. Mitchell<br /> | rowspan=8 | Democratic | nowrap rowspan=8 | May 19, 1980 âÂÂ<br/>Jan 3, 1995 | rowspan=2 | Appointed to finish term.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1982. | rowspan=3 | 29 |
|- style="height:2em" | | rowspan=3 | 29 | rowspan=3 | Re-elected in 1984.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 1988.Retired. | rowspan=3 | 30 |
|- style="height:2em" | | rowspan=3 | 30 | rowspan=3 | Re-elected in 1990.Retired.
|- style="height:2em" |
|- style="height:2em" ! rowspan=9 | 21 | rowspan=9 align=left | <br/>Olympia Snowe<br /> | rowspan=9 | Republican | nowrap rowspan=9 | Jan 3, 1995 âÂÂ<br/>Jan 3, 2013 | rowspan=3 | Elected in 1994. | rowspan=3 | 31 |
|- style="height:2em" | | rowspan=3 | 31 | rowspan=3 | Elected in 1996. | nowrap rowspan=15 nowrap | Jan 3, 1997 âÂÂ<br/>present | rowspan=15 | Republican | rowspan=15 align=right | <br/>Susan Collins<br /> ! rowspan=15 | 20
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 2000. | rowspan=3 | 32 |
|- style="height:2em" | | rowspan=3 | 32 | rowspan=3 | Re-elected in 2002.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 2006.Retired. | rowspan=3 | 33 |
|- style="height:2em" | | rowspan=3 | 33 | rowspan=3 | Re-elected in 2008.
|- style="height:2em" |
|- style="height:2em" ! rowspan=9 | 22 | rowspan=9 align=left | <br/>Angus King<br /> | rowspan=9 | Independent | nowrap rowspan=9 | Jan 3, 2013 âÂÂ<br/>present | rowspan=3 | Elected in 2012. | rowspan=3 | 34 |
|- style="height:2em" | | rowspan=3 | 34 | rowspan=3 | Re-elected in 2014.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 2018. | rowspan=3 | 35 |
|- style="height:2em" | | rowspan=3 | 35 | rowspan=3 | Re-elected in 2020.
|- style="height:2em" |
|- style="height:2em" | rowspan=3 | Re-elected in 2024. | rowspan=3 | 36 |
|- style="height:2em" | | rowspan=3 | 36 | rowspan=3 colspan=5 | To be determined in the 2026 election.
|- style="height:2em" |
|- style="height:2em" | colspan=5 | To be determined in the 2030 election. | 37 |