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 state governor. 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 two-year congressional term (up until the last senator who was not sworn in early after winning the November 2000 election) are listed at the end of the list with no number.
During the 106th Congress, the US Senate had a Republican majority.
U.S. Senate seniority| Rank | Senator (party-state) | Seniority date | Other factors |
|---|
| 1 | Strom Thurmond (R-SC) | November 7, 1956 |
| 2 | Robert Byrd (D-WV) | January 3, 1959 |
| 3 | Ted Kennedy (D-MA) | November 7, 1962 |
| 4 | Daniel Inouye (D-HI) | January 3, 1963 |
| 5 | Ernest Hollings (D-SC) | November 9, 1966 |
| 6 | Ted Stevens (R-AK) | December 24, 1968 |
| 7 | Bill Roth[8] (R-DE) | January 1, 1971 |
| 8 | Jesse Helms (R-NC) | January 3, 1973 | North Carolina 12th in population (1970) |
| 9 | Pete Domenici (R-NM) | New Mexico 37th in population (1970) |
| 10 | Joe Biden (D-DE) | Delaware 46th in population (1970) |
| 11 | Patrick Leahy (D-VT) | January 3, 1975 |
| 12 | John Chafee[9] (R-RI) | December 29, 1976 |
| 13 | Paul Sarbanes (D-MD) | January 3, 1977 | Former representative |
| 14 | Pat Moynihan[8] (D-NY) | New York 2nd in population (1970) |
| 15 | Richard Lugar (R-IN) | Indiana 11th in population (1970) |
| 16 | Orrin Hatch (R-UT) | Utah 36th in population (1970) |
| 17 | Max Baucus (D-MT) | December 15, 1978 |
| 18 | Thad Cochran (R-MS) | December 27, 1978 |
| 19 | John Warner (R-VA) | January 2, 1979 |
| 20 | Carl Levin (D-MI) | January 3, 1979 |
| 21 | Chris Dodd (D-CT) | January 3, 1981 | Former representative (6 years) - Connecticut 24th in population (1970) |
| 22 | Chuck Grassley (R-IA) | Former representative (6 years) - Iowa 25th in population (1970) |
| 23 | Arlen Specter (R-PA) | Pennsylvania 3rd in population (1970) |
| 24 | Don Nickles (R-OK) | Oklahoma 27th in population (1970) |
| 25 | Frank Murkowski (R-AK) | Alaska 50th in population (1970) |
| 26 | Frank Lautenberg[8][10] (D-NJ) | December 27, 1982 |
| 27 | Jeff Bingaman (D-NM) | January 3, 1983 |
| 28 | John Kerry (D-MA) | January 2, 1985 |
| 29 | Tom Harkin (D-IA) | January 3, 1985 | Former representative (10 years) |
| 30 | Phil Gramm (R-TX) | Former representative (6 years) |
| 31 | Mitch McConnell (R-KY) |
| 32 | Jay Rockefeller (D-WV) | January 15, 1985 |
| 33 | John Breaux (D-LA) | January 3, 1987 | Former representative (14 years) |
| 34 | Barbara Mikulski (D-MD) | Former representative (10 years) |
| 35 | Richard Shelby (R-AL) | Former representative (8 years) - Alabama 22nd in population (1980) |
| 36 | Tom Daschle (D-SD) | Former representative (8 years) - South Dakota 45th in population (1980) |
| 37 | John McCain (R-AZ) | Former representative (4 years) - Arizona 29th in population (1980) |
| 38 | Harry Reid (D-NV) | Former representative (4 years) - Nevada 43rd in population (1980) |
| 39 | Bob Graham (D-FL) | Former governor - Florida 7th in population (1980) |
| 40 | Kit Bond (R-MO) | Former governor - Missouri 15th in population (1980) |
| 41 | Kent Conrad (D-ND) |
| 42 | Slade Gorton[8] (R-WA) | January 3, 1989 | Previously a senator |
| 43 | Trent Lott (R-MS) | Former representative (16 years) |
| 44 | Jim Jeffords (R-VT) | Former representative (14 years) |
| 45 | Connie Mack[8] (R-FL) | Former representative (6 years) |
| 46 | Chuck Robb[8] (D-VA) | Former governor - Virginia 14th in population (1980) |
| 47 | Richard Bryan[8] (D-NV) | Former governor - Nevada 43rd in population (1980) |
| 48 | Bob Kerrey[8] (D-NE) | Former governor - Nebraska 35th in population (1980) |
| 49 | Herb Kohl (D-WI) | Wisconsin 16th in population (1980) |
| 50 | Joe Lieberman (ID-CT) | Connecticut 25th in population (1980) |
| 51 | Conrad Burns (R-MT) | Montana 44th in population (1980) |
| 52 | Daniel Akaka (D-HI) | May 16, 1990 |
| 53 | Bob Smith (R-NH) | December 7, 1990 |
| 54 | Larry Craig (R-ID) | January 3, 1991 | Former representative (6 years) |
| 55 | Paul Wellstone (D-MN) |
| 56 | Dianne Feinstein (D-CA) | November 10, 1992 |
| 57 | Byron Dorgan (D-ND) | December 15, 1992 |
| 58 | Barbara Boxer (D-CA) | January 3, 1993 | Former representative (10 years) |
| 59 | Judd Gregg (R-NH) | Former representative (8 years) Former governor |
| 60 | Ben Nighthorse Campbell (R-CO) | Former representative (6 years) |
| 61 | Paul Coverdell[11] (R-GA) | Georgia 11th in population (1990) |
| 62 | Russ Feingold (D-WI) | Wisconsin 16th in population (1990) |
| 63 | Patty Murray (D-WA) | Washington 18th in population (1990) |
| 64 | Bob Bennett (R-UT) | Utah 35th in population (1990) |
| 65 | Kay Bailey Hutchison (R-TX) | June 14, 1993 |
| 66 | Jim Inhofe (R-OK) | November 17, 1994 |
| 67 | Fred Thompson (R-TN) | December 2, 1994 |
| 68 | Olympia Snowe (R-ME) | January 3, 1995 | Former representative (16 years) |
| 69 | Mike DeWine (R-OH) | Former representative (8 years) - Ohio 7th in population (1990) |
| 70 | Jon Kyl (R-AZ) | Former representative (8 years) - Arizona 24th in population (1990) |
| 71 | Craig Thomas (R-WY) | Former representative (6 years) |
| 72 | Rick Santorum (R-PA) | Former representative (4 years) |
| 73 | Rod Grams[8] (R-MN) | Former representative (2 years) |
| 74 | John Ashcroft[8] (R-MO) | Former governor[12] |
| 75 | Spencer Abraham[8] (R-MI) | Michigan 8th in population (1990) |
| 76 | Bill Frist (R-TN) | Tennessee 17th in population (1990) |
| 77 | Ron Wyden (D-OR) | February 6, 1996 |
| 78 | Sam Brownback (R-KS) | November 7, 1996 |
| 79 | Pat Roberts (R-KS) | January 3, 1997 | Former representative (16 years) |
| 80 | Richard Durbin (D-IL) | Former representative (14 years) |
| 81 | Robert Torricelli (D-NJ) | Former representative (13 years) |
| 82 | Tim Johnson (D-SD) | Former representative (10 years) |
| 83 | Wayne Allard (R-CO) | Former representative (6 years) - Colorado 26th in population (1990) |
| 84 | Jack Reed (D-RI) | Former representative (6 years) - Rhode Island 43rd in population (1990) |
| 85 | Tim Hutchinson (R-AR) | Former representative (4 years) |
| 86 | Max Cleland (D-GA) | Georgia 11th in population (1990) |
| 87 | Mary Landrieu (R-LA) | Louisiana 21st in population (1990) |
| 88 | Jeff Sessions (R-AL) | Alabama 22nd in population (1990) |
| 89 | Gordon H. Smith (R-OR) | Oregon 29th in population (1990) |
| 90 | Chuck Hagel (R-NE) | Nebraska 36th in population (1990) |
| 91 | Susan Collins (R-ME) | Maine 38th in population (1990) |
| 92 | Mike Enzi (R-WY) | Wyoming 50th in population (1990) |
| 93 | Chuck Schumer (D-NY) | January 3, 1999 | Former representative (18 years) |
| 94 | Jim Bunning (R-KY) | Former representative (12 years) |
| 95 | Mike Crapo (R-ID) | Former representative (6 years) |
| 96 | Blanche Lincoln (D-AR) | Former representative (4 years) |
| 97 | George Voinovich (R-OH) | Former governor - Ohio 7th in population (1990) |
| 98 | Evan Bayh (D-IN) | Former governor - Indiana 14th in population (1990) |
| 99 | Peter Fitzgerald (R-IL) | Illinois 6th in population (1990) |
| 100 | John Edwards (D-NC) | North Carolina 10th in population (1990) |
| Lincoln Chafee (R-RI) | November 4, 1999 |
| Zell Miller (D-GA) | July 27, 2000 |
|
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. ^1971 U.S Census Report Contains 1970 Census results.
3. ^1981 U.S Census Report Contains 1980 Census results.
4. ^1991 U.S Census Report Contains 1990 Census results.
5. ^Terms of service of senators that will expire in 2001.
6. ^Terms of service of senators that will expire in 2003.
7. ^Terms of service of senators that will expire in 2005.
8. ^1 2 3 4 5 6 7 8 9 10 Retired or defeated in 2000 Election
9. ^John Chafee was set to retire but died of congestive heart failure on October 24, 1999.
10. ^Senator Lautenberg returned to the Senate in 2003 but cannot regain his previous seniority according to Senate Rules.
11. ^Senator Coverdell died of a cerebral hemorrhage on July 19, 2000.
12. ^Note that Jean Carnahan a, Democrat from Missouri and wife of Mel Carnahan who had also been posthumously elected in November 2000 was appointed to the Senate on December 4, 2000 to replace John Ashcroft, a Republican.