| Rank | Senator (party-state) | Seniority date | Other factors |
|---|
| 1 | William Rufus de Vane King (D-AL) [6] | December 14, 1819 | |
| 2 | Thomas Hart Benton (D-MO) | August 10, 1821 |
| 3 | Silas Wright, Jr. (D-NY) [7] | January 4, 1833 |
| 4 | Nathaniel Pitcher Tallmadge (W-NY) [8] | March 4, 1833 |
| 5 | Lewis Fields Linn (D-MO) [9] | October 25, 1833 |
| 6 | James Buchanan (D-PA) | December 6, 1834 |
| 7 | Robert John Walker (D-MS) | March 4, 1835 |
| 8 | William Cabell Rives (W-VA) | March 4, 1836 |
| 9 | Richard Henry Bayard (W-DE) | June 17, 1836 |
| 10 | Ambrose Hundley Sevier (D-AR) | September 18, 1836 | Former delegate |
| 11 | William Savin Fulton (D-AR) [10] |
| 12 | Thomas Clayton (W-DE) | January 9, 1837 |
| 13 | William Allen (D-OH) | March 4, 1837 |
| 14 | William Duhurst Merrick (W-MD) | January 4, 1838 |
| 15 | Albert Smith White (W-IN) | March 4, 1839 | Former representative |
| 16 | Benjamin Tappan (D-OH) | Ohio 5th in population (1830) |
| 17 | Samuel Shethar Phelps (W-VT) | Vermont 17th in population (1830) |
| 18 | John Henderson (W-MS) | Mississippi 22nd in population (1830) |
| 19 | Daniel Sturgeon (D-PA) | January 14, 1840 |
| 20 | Augustus Seymour Porter (W-MI) | January 20, 1840 |
| 21 | Jabez Williams Huntington (W-CT) | May 4, 1840 |
| 22 | Willie Person Mangum (W-NC) | November 25, 1840 |
| 23 | Isaac Chapman Bates (W-MA) | January 13, 1841 |
| 24 | Rufus Choate (W-MA) | February 23, 1841 |
| 25 | Levi Woodbury (D-NH) | March 4, 1841 | Former senator (5 years) |
| 26 | John M. Berrien (W-GA) | Former senator (4 years) |
| 27 | William Segar Archer (W-VA) | Former representative (15 years) |
| 28 | George Evans (W-ME) | Former representative (11 years) |
| 29 | William Woodbridge (W-MI) | Former delegate (1 year) |
| 30 | James Turner Morehead (W-KY) | Former governor |
| 31 | Jacob Welsh Miller (W-NJ) | New Jersey 14th in population (1830) |
| 32 | Alexander Barrow (W-LA) | Louisiana 19th in population (1830) |
| 33 | Samuel McRoberts (D-IL) [11] | Illinois 20th in population (1830) |
| 34 | James F. Simmons (W-RI) | Rhode Island 23rd in population (1830) |
| 35 | Arthur Pendleton Bagby (D-AL) | November 24, 1841 |
| 36 | William Sprague III (W-RI) [12] | February 18, 1842 |
| 37 | John Jordan Crittenden (W-KY) | March 31, 1842 |
| 38 | William Lewis Dayton (W-NJ) | July 2, 1842 |
| 39 | George McDuffie (D-SC) | December 23, 1842 |
| 40 | John Milton Niles (D-CT) | March 4, 1843 | Former senator |
| 41 | James Alfred Pearce (W-MD) | Former representative (6 years); Maryland 15th in population (1840) |
| 42 | Charles Gordon Atherton (D-NH) | Former representative (6 years); New Hampshire 22nd in population (1840) |
| 43 | Edward Allen Hannegan (D-IN) | Former representative (4 years) |
| 44 | Walter Terry Colquitt (D-GA) | Former representative (1 year) |
| 45 | William Henry Haywood, Jr. (D-NC) | North Carolina 7th in population (1840) |
| 46 | Daniel Elliott Huger (D-SC) | South Carolina 11th in population (1840) |
| 47 | Sidney Breese (D-IL) | Illinois 14th in population (1840) |
| 48 | William Upham (W-VT) | Vermont 21st in population (1840) |
| David Rice Atchison (D-MO) | October 14, 1843 |
| 49 | Ephraim Hubbard Foster (W-TN) | October 17, 1843 | Former senator |
| 50 | Spencer Jarnagin (W-TN) |
| 51 | John Fairfield (D-ME) | December 4, 1843 | Maine 13th in population (1840) |
| James Semple (D-IL) | Illinois 14th in population (1840) |
| John Brown Francis (LO-RI) | January 25, 1844 |
| 52 | Henry Johnson (W-LA) | February 12, 1844 |
| Dixon Hall Lewis (D-AL) | April 22, 1844 |
| Chester Ashley (D-AR) | November 8, 1844 |
| Henry A. Foster (D-NY) [13] | November 30, 1844 | Former representative |
| Daniel Stevens Dickinson (D-NY) |
| John Adams Dix (D-NY) | January 27, 1845 |
|
