Here’s a look at the top 25 longest-serving senators in United States history.
The Top Twenty-Five as of 9/23/2015:
Names in bold are currently serving in the U.S. Senate
1) Robert C. Byrd (D-WV), 51 years, 5 months, 26 days
January 3, 1959 to June 28, 2010
2) Daniel K. Inouye (D-HI), 49 years, 11 months, 14 days
January 3, 1963 to December 17, 2012
3) Strom Thurmond (R-SC), 47 years, 5 months, 8 days
December 14, 1954 to April 4, 1956
November 7, 1956 to January 3, 2003
4) Edward M. Kennedy (D-MA), 46 years, 9 months, 19 days
November 7, 1962 until his death on August 25, 2009
5) Carl T. Hayden (D-AZ), 41 years, 9 months, 30 days
March 4, 1927 to January 2, 1969
6) John C. Stennis (D-MS), 41 years, 1 month, 29 days
November 5, 1947 to January 2, 1989
7) Patrick Leahy (D-VT), 40 years, 8 months, 21 days as of 9/23/2015
January 3, 1975 to present
8) Theodore F. Stevens (R-AK), 40 years, 10 days
December 24, 1968 to January 3, 2009
9) Orrin Hatch (R-UT), 38 years, 8 months, 21 days as of 9/23/2015
January 3, 1977 to present
10) Ernest F. Hollings (D-SC), 38 years, 1 month, 25 days
November 9, 1966 to January 3, 2005
11) Richard B. Russell (D-GA), 38 years, 10 days
January 12, 1933 to January 21, 1971
12) Russell Long (D-LA), 38 years, 3 days
December 31, 1948 to January 2, 1987
13) Francis E. Warren (R-WY), 37 years, 4 days
November 18, 1890 to March 3, 1893
March 4, 1895 to November 24, 1929
14) Thad Cochran (R-MS), 36 years, 8 months, 28 days as of 9/23/2015
December 27, 1978 to present
15) James O. Eastland (D-MS), 36 years, 2 months, 24 days
June 30, 1941 to September 28, 1941
January 3, 1943 to December 27, 1978
16) Warren Magnuson (D-WA), 36 years, 20 days
December 14, 1944 to January 2, 1981
17) Joseph R. Biden, Jr. (D-DE), 36 years, 13 days
January 3, 1973 to January 20, 2009
18) Pete V. Domenici (R-NM), 36 years
January 3, 1973 to January 3, 2009
18) Richard Lugar (R-IN), 36 years
January 3, 1977 to January 3, 2013
18) Claiborne Pell (D-RI), 36 years
January 3, 1961 to January 3, 1997
18) Carl Levin (D-MI), 36 years
January 3, 1979 to January 3, 2015
22) Kenneth McKellar (D-TN), 35 years, 10 months
March 4, 1917 to January 2, 1953
23) Milton R. Young (R-ND), 35 years, 9 months, 22 days
March 12, 1945 to January 3, 1981
24) Ellison D. Smith (D-SC), 35 years, 8 months, 13 days
March 4, 1909 to November 17, 1944
25) Allen Joseph Ellender (D-LA), 35 years, 6 months, 24 days
January 3, 1937 to July 27, 1972