These 25 individuals have served the longest U.S. Senate terms as of June 18, 2018.
| Senator | Dates of Service | Length of Service |
|---|---|---|
|
1. Robert C. Byrd (D-WV) |
Jan 3, 1959 to Jun 28, 2010 |
51 years, 5 months, 26 days |
|
2. Daniel K. Inouye (D-HI) |
Jan 3, 1963 to Dec 17, 2012 |
49 years, 11 months, 15 days |
|
3. Strom Thurmond (R-SC) |
Dec 14, 1954 to Apr 4, 1956 |
47 years, 5 months, 8 days |
|
4. Edward M. Kennedy (D-MA) |
Nov 7, 1962 to Aug 25, 2009 |
46 years, 9 months, 19 days |
|
5. Patrick J. Leahy (D-VT) |
Jan 3, 1975 to present |
43 years, 5 months, 16 days |
|
6. Carl T. Hayden (D-AZ) |
Mar 4, 1927 to Jan 3, 1969 |
41 years, 9 months, 30 days |
|
7. Orrin Hatch (R-UT) |
Jan 3, 1977 to present |
41 years, 5 months, 16 days |
|
8. John Stennis (D-MS) |
Nov 5, 1947 to Jan 3, 1989 |
41 years, 1 month, 29 days |
|
9. Ted Stevens (R-AK) |
Dec 24, 1968 to Jan 3, 2009 |
40 years, 10 days |
|
10. Thad Cochran (R-MS) |
Dec 27, 1978 to April 1, 2018 |
39 years, 3 months, 6 days |
|
11. Ernest F. Hollings (D-SC) |
Nov 9, 1966 to Jan 3, 2005 |
38 years, 1 month, 25 days |
|
12. Richard B. Russell (D-GA) |
Jan 12, 1933 to Jan 21, 1971 |
38 years, 10 days |
|
13. Russell Long (D-LA) |
Dec 31, 1948 to Jan 3, 1987 |
38 years, 3 days |
|
14. Charles E. Grassley (R-IA) |
Jan 3, 1981 to present |
37 years, 5 months, 16 days |
|
15. Francis E. Warren (R-WY) |
Nov 18, 1890 to Mar 3, 1893 |
37 years, 4 days |
|
16. James Eastland (D-MS) |
Jun 30, 1941 to Sep 28, 1941 |
36 years, 2 months, 24 days |
|
17. Warren Magnuson (D-WA) |
Dec 14, 1944 to Jan 3, 1981 |
36 years, 20 days |
|
18. Joseph R. Biden, Jr. (D-DE) |
Jan 3, 1973 to Jan 15, 2009 |
36 years, 13 days |
|
19. Pete V. Domenici (R-NM) |
Jan 3, 1973 to Jan 3, 2009 |
36 years |
|
19. Carl Levin (D-MI) |
Jan 3, 1979 to Jan 3, 2015 |
36 years |
|
19. Richard Lugar (R-IN) |
Jan 3, 1977 to Jan 3, 2013 |
36 years |
|
19. Claiborne Pell (D-RI) |
Jan 3, 1961 to Jan 3, 1997 |
36 years |
|
23. Kenneth D. McKellar (D-TN) |
Mar 4, 1917 to Jan 3, 1953 |
35 years, 10 months |
|
24. Milton R. Young (R-ND) |
Mar 12, 1945 to Jan 3, 1981 |
35 years, 9 months, 22 days |
|
25. Ellison D. Smith (D-SC) |
Mar 4, 1909 to Nov 17, 1944 |
35 years, 8 months, 13 days |
