This is a list of United States senators from Maryland, which ratified the United States Constitution April 28, 1788, becoming the seventh state to do so. To provide for continuity of government, the framers divided senators into staggered classes that serve six-year terms, and Maryland's senators are in the first and third classes. Before the passage of the Seventeenth Amendment to the United States Constitution in 1913, which allowed for direct election of senators, Maryland's senators were chosen by the Maryland General Assembly, which ratified the amendment on April 1, 2010. Until the assembly appointed George L. Wellington of Cumberland in 1897, senators in class 3 were chosen from the Eastern Shore while senators in class 1 were chosen from the remainder of the state. Barbara Mikulski has been Maryland's longest-serving senator (1987–2017).
List of senators
|- style="height:2em" ! rowspan=2 | 1 | rowspan=2 align=left | Charles Carroll | rowspan=2 | Pro-Admin. | rowspan=2 nowrap | Mar 4, 1789 –Nov 30, 1792 | Elected in 1788. | 1 | | rowspan=5 | 1 | rowspan=5 | Elected in 1788. | rowspan=9 nowrap | Mar 4, 1789 –Dec 10, 1797 | rowspan=9 | Pro-Admin. | rowspan=9 align=right | John Henry ! rowspan=9 | 1
|- style="height:2em" | Re-elected in 1791.Resigned to remain in the Maryland Senate. | rowspan=7 | 2 | rowspan=3
|- style="height:2em" | colspan=3 | Vacant | nowrap | Nov 30, 1792 –Jan 10, 1793
|- style="height:2em" ! rowspan=3 | 2 | rowspan=3 align=left | Richard Potts | rowspan=3 | Pro-Admin. | rowspan=3 nowrap | Jan 10, 1793 –Oct 24, 1796 | rowspan=3 | Elected to finish Carroll's term.Resigned.
|- style="height:2em"
|- style="height:2em" | rowspan=3 | rowspan=8 | 2 | rowspan=4 | Re-elected in 1795.Resigned to become Governor of Maryland.
|- style="height:2em" | colspan=3 | Vacant | nowrap | Oct 24, 1796 –Nov 30, 1796
|- style="height:2em" ! rowspan=8 | 3 | rowspan=8 align=left | John Eager Howard | rowspan=8 | Federalist | rowspan=8 nowrap | Nov 30, 1796 –Mar 3, 1803 | Elected to finish Carroll's term.
|- style="height:2em" | rowspan=7 | Re-elected in 1796.Lost re-election. | rowspan=7 | 3 | rowspan=2
|- style="height:2em" | rowspan=2 | Elected to finish Henry's term.Resigned. | rowspan=2 nowrap | Dec 11, 1797 –Dec 1, 1800 | rowspan=2 | Federalist | rowspan=2 align=right | James Lloyd ! rowspan=2 | 2
|- style="height:2em" | rowspan=3
|- style="height:2em"
| nowrap | Dec 1, 1800 –Dec 12, 1800 | colspan=3 | Vacant
|- style="height:2em" | Elected to finish Henry's term. | rowspan=2 nowrap | Dec 12, 1800 –Nov 19, 1801 | rowspan=2 | Federalist | rowspan=2 align=right | William Hindman ! rowspan=2 | 3
|- style="height:2em" | rowspan=2 | rowspan=6 | 3 | Appointed to fill the vacancy after the Legislature failed to elect.Retired when successor elected.
|- style="height:2em" | rowspan=3 | Elected to finish term.Resigned to become Governor of Maryland. | rowspan=3 nowrap | Nov 19, 1801 –Nov 12, 1806 | rowspan=3 | Democratic-Republican | rowspan=3 align=right | Robert Wright ! rowspan=3 | 4
|- style="height:2em" ! rowspan=9 | 4 | rowspan=9 align=left | Samuel Smith | rowspan=9 | Democratic-Republican | rowspan=9 nowrap | Mar 4, 1803 –Mar 3, 1815 | rowspan=5 | Elected in 1802., citing Votes and Proceedings of the Maryland State Senate, 1802. 10. | rowspan=5 | 4
|- style="height:2em" | rowspan=3
|- style="height:2em"
| nowrap | Nov 12, 1806 –Nov 25, 1806 | colspan=3 | Vacant
|- style="height:2em" | Elected to finish Wright's term. | rowspan=4 nowrap | Nov 25, 1806 –Mar 3, 1813 | rowspan=4 | Democratic-Republican | rowspan=4 align=right | Philip Reed ! rowspan=4 | 5
|- style="height:2em" | | rowspan=3 | 4 | rowspan=3 | Re-elected in 1806.
|- style="height:2em" | rowspan=4 | Re-elected in 1809., citing The Hornet (Fredericktown, Md.). Nov 29, 1809. | rowspan=4 | 5
|- style="height:2em"
|- style="height:2em" | rowspan=2 | rowspan=7 | 5 | Legislature failed to elect. | nowrap | Mar 3, 1813 –May 21, 1813 | colspan=3 | Vacant
|- style="height:2em" | rowspan=6 | Elected in 1813 to finish term. | rowspan=6 nowrap | May 21, 1813 –Mar 3, 1819 | rowspan=6 | Federalist | rowspan=6 align=right | Robert Henry Goldsborough ! rowspan=6 | 6
|- style="height:2em" | colspan=3 | Vacant | nowrap | Mar 4, 1815 –Jan 29, 1816 | Legislature failed to elect | rowspan=8 | 6 | rowspan=4
|- style="height:2em" ! 5 | align=left | Robert Goodloe Harper | | Federalist | nowrap | Jan 29, 1816 –Dec 6, 1816 | Elected to finish term.Resigned.
|- style="height:2em" | colspan=3 | Vacant | nowrap | Dec 6, 1816 –Dec 20, 1816
|- style="height:2em" ! rowspan=3 | 6 | rowspan=3 align=left | Alexander Hanson | rowspan=3 | Federalist | rowspan=3 nowrap | Dec 20, 1816 –Apr 23, 1819 | rowspan=3 | Elected to finish the vacant term that happened from 1815 to 1816.Died.
|- style="height:2em"
|- style="height:2em" | rowspan=3 | rowspan=7 | 6 | rowspan=2 | Legislature did not elect until after the term began. | rowspan=2 nowrap | Mar 4, 1819 –Dec 20, 1819 | rowspan=2 colspan=3 | Vacant
|- style="height:2em" | colspan=3 | Vacant | nowrap | Apr 23, 1819 –Dec 21, 1819
|- style="height:2em" ! rowspan=2 | 7 | rowspan=2 align=left | William Pinkney | rowspan=2 | Democratic-Republican | rowspan=2 nowrap | Dec 20, 1819 –Feb 25, 1822 | Elected in 1819 to finish the vacant term that happened from 1815 to 1816. | rowspan=5 | Elected late in 1819. | rowspan=6 nowrap | Dec 21, 1819 –Jan 14, 1826 | rowspan=5 | Democratic-Republican | rowspan=6 align=right | Edward Lloyd ! rowspan=6 | 7
|- style="height:2em" | Re-elected in 1821.Died. | rowspan=7 | 7 | rowspan=3
|- style="height:2em" | colspan=3 | Vacant | nowrap | Feb 25, 1822 –Dec 17, 1822
|- style="height:2em" ! rowspan=8 | 8 | rowspan=8 align=left | Samuel Smith | rowspan=2 | Democratic-Republican | rowspan=8 nowrap | Dec 17, 1822 –Mar 3, 1833 | rowspan=5 | Elected to finish Pinkney's term.
|- style="height:2em"
|- style="height:2em" | rowspan=6 | Jacksonian | rowspan=3 | rowspan=5 | 7 | Re-elected in 1825.Resigned. | | Jacksonian
|- style="height:2em"
| nowrap | Jan 14, 1826 –Jan 24, 1826 | colspan=3 | Vacant
|- style="height:2em" | rowspan=3 | Elected to finish Lloyd's term. | rowspan=5 nowrap | Jan 24, 1826 –Dec 20, 1834 | rowspan=5 | NationalRepublican | rowspan=5 align=right | Ezekiel F. Chambers ! rowspan=5 | 8
|- style="height:2em" | rowspan=3 | Re-elected in 1827. | rowspan=3 | 8
|- style="height:2em"
|- style="height:2em" | | rowspan=7 | 8 | rowspan=2 | Re-elected in 1831.Resigned to become judge of the Maryland Court of Appeals.
|- style="height:2em" ! rowspan=7 | 9 | rowspan=7 align=left | Joseph Kent | rowspan=6 | NationalRepublican | rowspan=7 nowrap | Mar 4, 1833 –Nov 24, 1837 | rowspan=7 | Elected in 1833.Died. | rowspan=9 | 9 | rowspan=3
|- style="height:2em"
| nowrap | Dec 20, 1834 –Jan 13, 1835 | colspan=3 | Vacant
|- style="height:2em" | rowspan=2 | Elected to finish Chambers's term.Died. | rowspan=2 nowrap | Jan 13, 1835 –Oct 5, 1836 | rowspan=2 | NationalRepublican | rowspan=2 align=right | Robert Henry Goldsborough ! rowspan=2 | 9
|- style="height:2em" | rowspan=3
|- style="height:2em"
| nowrap | Oct 5, 1836 –Dec 31, 1836 | colspan=3 | Vacant
|- style="height:2em" | Elected to finish Chambers's term. | rowspan=5 nowrap | Dec 31, 1836 –Oct 24, 1840 | | NationalRepublican | rowspan=5 align=right | John S. Spence ! rowspan=5 | 10
|- style="height:2em" | | Whig | rowspan=3 | rowspan=7 | 9 | rowspan=4 | Re-elected in 1837.Died. | rowspan=4 | Whig
|- style="height:2em" | colspan=3 | Vacant | nowrap | Nov 24, 1837 –Jan 4, 1838
|- style="height:2em" ! rowspan=6 | 10 | rowspan=6 align=left | William Duhurst Merrick | rowspan=6 | Whig | rowspan=6 nowrap | Jan 4, 1838 –Mar 3, 1845 | Elected to finish Kent's term.
|- style="height:2em" | rowspan=5 | Re-elected in 1839. | rowspan=5 | 10 | rowspan=3
|- style="height:2em"
| nowrap | Oct 24, 1840 –Jan 5, 1841 | colspan=3 | Vacant
|- style="height:2em" | rowspan=2 | Elected to finish Spence's term. | rowspan=2 nowrap | Jan 5, 1841 –Mar 3, 1843 | rowspan=2 | Whig | rowspan=2 align=right | John Leeds Kerr ! rowspan=2 | 11
|- style="height:2em"
|- style="height:2em" | | rowspan=3 | 10 | rowspan=3 | Elected in 1843. | rowspan=13 nowrap | Mar 4, 1843 –Dec 20, 1862 | rowspan=10 | Whig | rowspan=13 align=right | James Pearce ! rowspan=13 | 12
|- style="height:2em" ! rowspan=3 | 11 | rowspan=3 align=left | Reverdy Johnson | rowspan=3 | Whig | rowspan=3 nowrap | Mar 4, 1845 –Mar 7, 1849 | rowspan=3 | Election year unknown.Resigned to become U.S. Attorney General. | rowspan=6 | 11
|- style="height:2em"
|- style="height:2em" | rowspan=4 | rowspan=6 | 11 | rowspan=6 | Re-elected in 1849.
|- style="height:2em" | colspan=3 | Vacant | nowrap | Mar 7, 1849 –Dec 6, 1849
|- style="height:2em" ! 12 | align=left | David Stewart | | Democratic | nowrap | Dec 6, 1849 –Jan 12, 1850 | Appointed to continue Johnson's term.Retired when successor elected.
|- style="height:2em" ! rowspan=4 | 13 | rowspan=4 align=left | Thomas Pratt | rowspan=4 | Whig | rowspan=4 nowrap | Jan 12, 1850 –Mar 3, 1857 | Elected to finish Johnson's term.
|- style="height:2em" | rowspan=3 | Re-elected in 1851. | rowspan=3 | 12
|- style="height:2em"
|- style="height:2em" | | rowspan=3 | 12 | rowspan=3 | Re-elected in 1855.
|- style="height:2em" ! rowspan=5 | 14 | rowspan=5 align=left | Anthony Kennedy | rowspan=2 | American | rowspan=5 nowrap | Mar 4, 1857 –Mar 3, 1863 | rowspan=5 | Election year unknown. | rowspan=5 | 13 | | rowspan=3 | Democratic
|- style="height:2em"
|- style="height:2em" | rowspan=3 | Union | rowspan=3 | rowspan=7 | 13 | Re-elected in 1860.Died.
|- style="height:2em"
| nowrap | Dec 20, 1862 –Dec 29, 1862 | colspan=3 | Vacant
|- style="height:2em" | rowspan=2 | Appointed to continue Pearce's term.Elected in 1864 to finish Pearce's term.Died. | rowspan=2 nowrap | Dec 29, 1862 –Feb 14, 1865 | rowspan=2 | Union | rowspan=2 align=right | Thomas Holliday Hicks ! rowspan=2 | 13
|- style="height:2em" ! rowspan=6 | 15 | rowspan=6 align=left | Reverdy Johnson | rowspan=2 | Union | rowspan=6 nowrap | Mar 4, 1863 –Jul 10, 1868 | rowspan=6 | Election year unknown.Resigned to become U.S. Ambassador to the United Kingdom of Great Britain and Ireland. | rowspan=8 | 14 | rowspan=2
|- style="height:2em" | rowspan=2 | | rowspan=2 nowrap | Feb 14, 1865 –Mar 9, 1865 | rowspan=2 colspan=3 | Vacant
|- style="height:2em" | rowspan=4 | Democratic | rowspan=2
|- style="height:2em" | Elected to finish Pearce's term. | nowrap | Mar 9, 1865 –Mar 3, 1867 | | Unconditional Union | rowspan=1 align=right | John Creswell ! 14
|- style="height:2em" | rowspan=4 | rowspan=6 | 14 | Philip F. Thomas (D) was elected but failed to qualify due to his support for the Confederacy. | nowrap | Mar 4, 1867 –Mar 7, 1868 | colspan=3 | Vacant
|- style="height:2em" | rowspan=5 | Elected to finish Thomas's term. | rowspan=5 nowrap | Mar 7, 1868 –Mar 3, 1873 | rowspan=5 | Democratic | rowspan=5 align=right | George Vickers ! rowspan=5 | 15
|- style="height:2em" | colspan=3 | Vacant | nowrap | Jul 10, 1868 –Jul 13, 1868
|- style="height:2em" ! 16 | align=left | William Whyte | | Democratic | nowrap | Jul 13, 1868 –Mar 3, 1869 | Appointed to finish Johnson's term.Retired.
|- style="height:2em" ! rowspan=3 | 17 | rowspan=3 align=left | William T. Hamilton | rowspan=3 | Democratic | rowspan=3 nowrap | Mar 4, 1869 –Mar 3, 1875 | rowspan=3 | Election year unknown.Retired to run for governor. | rowspan=3 | 15
|- style="height:2em"
|- style="height:2em" | | rowspan=3 | 15 | rowspan=3 | Election year unknown. | rowspan=3 nowrap | Mar 4, 1873 –Mar 3, 1879 | rowspan=3 | Democratic | rowspan=3 align=right | George R. Dennis ! rowspan=3 | 16
|- style="height:2em" ! rowspan=3 | 18 | rowspan=3 align=left | William Whyte | rowspan=3 | Democratic | rowspan=3 nowrap | Mar 4, 1875 –Mar 3, 1881