Order of service is based on the commencement of the senator's first term. Behind this is former service as a senator (only giving the senator seniority within his or her new incoming class), service as vice president, a House member, a cabinet secretary, or a governor of a state. The final factor is the population of the senator's state.[1][2][3][4]
Senators who were sworn in during the middle of the Congress (up until the last senator who was not sworn in early after winning the November 1898 election) are listed at the end of the list with no number.
U.S. Senate seniority| Rank | Senator (party-state) | Seniority date | Other factors |
|---|
| 1 | Justin S. Morrill (R-VT) | March 4, 1867 |
| 2 | William B. Allison (R-IA) | March 4, 1873 | Former representative |
| 3 | John P. Jones (R-NV) | |
| 4 | Francis Cockrell (D-MO) | March 4, 1875 |
| 5 | George F. Hoar (R-MA) | March 4, 1877 | Former representative |
| 6 | Isham G. Harris (D-TN) | Former governor |
| 7 | John Tyler Morgan (D-AL) |
| 8 | George G. Vest (D-MO) | March 4, 1879 | Missouri 5th in population (1870) |
| 9 | Orville H. Platt (R-CT) | Connecticut 25th in population (1870) |
| 10 | John Sherman (R-OH) | March 4, 1881 | Previously a senator |
| 11 | Eugene Hale (R-ME) | Former representative (10 years) |
| 12 | Joseph Hawley (R-CT) | Former representative (5 years) |
| 13 | James Z. George (D-MS) | Mississippi 18th in population (1870) |
| 14 | Arthur P. Gorman (D-MD) | Maryland 20th in population (1870) |
| 15 | William P. Frye (R-ME) | March 18, 1881 | |
| 16 | Nelson Aldrich (R-RI) | October 5, 1881 |
| 17 | Shelby Moore Cullom (R-IL) | March 4, 1883 |
| 18 | Henry M. Teller (D-CO) | March 4, 1885 | Previously a senator |
| 19 | James K. Jones (D-AR) | |
| 20 | George Gray (D-DE) | March 18, 1885 |
| 21 | James H. Berry (D-AR) | March 20, 1885 |
| 22 | William M. Stewart (R-NV) | March 4, 1887 | Previously a senator (11 years) |
| 23 | David Turpie (D-IN) | Previously a senator (1 month) |
| 24 | John W. Daniel (D-VA) | Former representative |
| 25 | William B. Bate (D-TN) | Former governor, Tennessee 12th in population (1880) |
| 26 | Cushman Davis (R-MN) | Former governor, Minnesota 26th in population (1880) |
| 27 | Matthew Quay (R-PA) | Pennsylvania 2nd in population (1880) |
| 28 | Charles J. Faulkner (D-WV) | West Virginia 29th in population (1880) |
| 29 | Samuel Pasco (D-FL) | May 19, 1887 |
| 30 | James McMillan (R-MI) | March 4, 1889 | Michigan 9th in population (1880) |
| 31 | Edward O. Wolcott (R-CO) | Colorado 35th in population (1880) |
| 32 | William E. Chandler (R-NH) | June 18, 1889 | |
| 33 | Richard F. Pettigrew (SR-SD) | November 2, 1889 |
| 34 | George L. Shoup (R-ID) | December 18, 1890 |
| 35 | Jacob H. Gallinger (R-NH) | March 4, 1891 | Former representative (4 years) |
| 36 | Henry C. Hansbrough (R-ND) | Former representative (2 years) |
| 37 | James H. Kyle (R-SD) | |
| 38 | Redfield Proctor (R-VT) | November 2, 1891 |
| 39 | Roger Q. Mills (D-TX) | March 23, 1892 |
| 40 | Donelson Caffery (D-LA) | December 31, 1892 |
| 41 | William Lindsay (D-KY) | February 15, 1893 |
| 42 | Henry Cabot Lodge (R-MA) | March 4, 1893 | Former representative (6 years) |
| 43 | John L. Mitchell (D-WI) | Former representative (2 years) |
| 44 | Edward Murphy, Jr. (D-NY) | New York 1st in population (1890) |
| 45 | James Smith, Jr. (D-NJ) | New Jersey 18th in population (1890) |
| 46 | Stephen M. White (D-CA) | California 22nd in population (1890) |
| 47 | William V. Allen (Pop-NE) | Nebraska 26th in population (1890) |
| 48 | William N. Roach (D-ND) | North Dakota 41st in population (1890) |
| 49 | George C. Perkins (R-CA) | July 26, 1893 | |
| 50 | Lee Mantle (SR-MT) | January 16, 1895 |
| 51 | Julius C. Burrows (R-MI) | January 23, 1895 |
| 52 | Clarence D. Clark (R-WY) | January 24, 1895 | Former representative |
| 53 | Jeter C. Pritchard (R-NC) | |
| 54 | John L. Wilson (R-WA) | February 19, 1895 |
| 55 | Edward C. Walthall (D-MS) | March 4, 1895 | Previously a senator (9 years) |
| 56 | William J. Sewell (R-NJ) | Previously a senator (6 years) |
| 57 | Francis E. Warren (R-WY) | Previously a senator (3 years) |
| 58 | Horace Chilton (D-TX) | Previously a senator (2 years) |
| 59 | Thomas Carter (R-MT) | Former delegate, former representative |
| 60 | Stephen Elkins (R-WV) | Former delegate, former cabinet member |
| 61 | John H. Gear (R-IA) | Former governor, Iowa 10th in population (1890) |
| 62 | Knute Nelson (R-MN) | Former governor, Minnesota 20th in population (1890) |
| 63 | Benjamin Tillman (D-SC) | Former governor, South Carolina 23rd in population (1890) |
| 64 | George P. Wetmore (R-RI) | Former governor, Rhode Island 36th in population (1890) |
| 65 | Augustus O. Bacon (D-GA) | Georgia 12th in population (1890) |
| 66 | Thomas S. Martin (D-VA) | Virginia 15th in population (1890) |
| 67 | Marion Butler (Pop-NC) | North Carolina 16th in population (1890) |
| 68 | Lucien Baker (Pop-KS) | Kansas 19th in population (1890) |
| 69 | John M. Thurston (R-NE) | Nebraska 26th in population (1890) |
| 70 | George McBride (R-OR) | Oregon 38th in population (1890) |
| 71 | Frank Cannon (SR-UT) | January 22, 1896 | |
| 72 | Richard Kenney (D-DE) | January 19, 1897 |
| 73 | John C. Spooner (R-WI) | March 4, 1897 | Previously a senator (6 years) |
| 74 | Thomas C. Platt (R-NY) | Previously a senator (2 months) |
| 75 | William E. Mason (R-IL) | Former representative (4 years) |
| 76 | William A. Harris (Pop-KS) | Former representative (2 years), Kansas 19th in population (1890) |
| 77 | George L. Wellington (R-MD) | Former representative (2 years), Maryland 27th in population (1890) |
| 78 | Joseph Rawlins (R-UT) | Former delegate |
| 79 | Joseph Foraker (R-OH) | Former governor, Ohio 4th in population (1890) |
| 80 | Samuel McEnery (D-LA) | Former governor, Louisiana 25th in population (1890) |
| 81 | Boies Penrose (R-PA) | Pennsylvania 2nd in population (1890) |
| 82 | Charles W. Fairbanks (R-IN) | Indiana 8th in population (1890) |
| 83 | William Deboe (R-KY) | Kentucky 11th in population (1890) |
| 84 | Alexander Clay (D-GA) | Georgia 12th in population (1890) |
| 85 | Edmund Pettus (D-AL) | Alabama 17th in population (1890) |
| 86 | Joseph H. Earle (D-SC) | South Carolina 23rd in population (1890) |
| 87 | George Turner (SR-WA) | Washington 34th in population (1890) |
| 88 | Henry Heitfeld (Pop-ID) | Idaho 43rd in population (1890) |
| Mark Hanna (R-OH) | March 6, 1897 | |
| 89 | Stephen Mallory (D-FL) | May 15, 1897 |
| John L. McLaurin (D-SC) | June 1, 1897 |
| Thomas B. Turley (D-TN) | July 20, 1897 |
| Hernando Money (D-MS) | October 8, 1897 |
| William V. Sullivan (D-MS) | May 31, 1898 |
| 90 | Joseph Simon (R-OR) | October 8, 1898 |
| Jonathan Ross (R-VT) | January 11, 1899 |
|
1. ^[https://www.senate.gov/artandhistory/history/common/briefing/senators_chronological.htm A Chronological List of United States Senators 1789-Present], via www.Senate.gov
2. ^1871 U.S Census Report Contains 1870 Census results
3. ^1881 U.S Census Report Contains 1880 Census results
4. ^1891 U.S Census Report Contains 1890 Census results
5. ^Terms of service of senators that will expire in 1899.
6. ^Terms of service of senators that will expire in 1901.
7. ^Terms of service of senators that will expire in 1903.