What Senators have served the longest in the US Senate?
US Senators do not have term limits and some have managed to keep their jobs well into their golden years serving for decades. Here are the longest serving.

In order to become a US Senator, you must first be at least 30 years old. Then convince your fellow Americans in your state to vote for you for a six-year term. Some have successfully done this time and again keeping their position in the upper chamber for decades on end.
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While most US Senators take office in their early 50s, a lengthy service means that they can reach very old age in office. Three of the top twenty-five longest serving Senators are still in their jobs. Only one of them will have to face off a challenger this year, Chuck Grassley from Iowa.
But even if he should be victorious, a fairly likely outcome as he’s been well ahead in the polls throughout the 2022 campaign, he still won’t be the oldest currently serving Senator. Grassley would need another two terms in office to beat the current record of service and age to boot. Here’s a look.
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The longest serving US Senators
Senator Robert C Byrd is the current record holder for the longest-serving US Senator. He served for a little more than five decades in the upper chamber of the US Congress elected for the first of nine times in 1958. He was in office for 51 years, 5 months, 26 days until his death in 2010 at the age of 92. He is also the longest-serving member of the US congress elected to the House of Representatives in 1952.
The three currently longest-serving US Senators in order are Democratic Senator from Vermont Patrick J. Leahy, followed by Republican Senators Chuck Grassley from Iowa and Mitch McConnell from Kentucky. Between them they have a combined service of nearly 127 years. They are currently third, eight and fifteenth, respectively, on the list of the top twenty-five longest-serving US Senators.
Ten longest-serving US Senators
1 | Robert C Byrd (D-WV) | Jan 3, 1959 - Jun 28, 2010 | 51 years, 5 months, 26 days |
2 | Daniel K Inouye (D-HI) | Jan 3, 1963 - Dec 17, 2012 | 49 years, 11 months, 15 days |
3 | Patrick J Leahy (D-VT) | Jan 3, 1975 - present | 47 years and counting |
4 | Strom Thurmond (D, R-SC) | Dec 14, 1954 - Jan 3, 2003 | 47 years, 5 months, 8 days |
5 | Edward M Kennedy (Ted) (D-MA) | Nov 7, 1962 - Aug 25, 2009 | 46 years, 9 months, 19 days |
6 | Orrin G Hatch (R-UT) | Jan 3, 1977 - Jan 3, 2019 | 42 years |
7 | Carl T Hayden (D-AZ) | Mar 4, 1927 - Jan 3, 1969 | 41 years, 10 months |
8 | Chuck Grassley (R-IA) | Jan 3, 1981 - present | 41 years and counting |
9 | John C Stennis (D-MS) | Nov 5, 1947 - Jan 3, 1989 | 41 years, 1 month, 29 days |
10 | Ted Stevens (R-AK) | Dec 24, 1968 - Jan 3, 2009 | 40 years, 10 days |
Who is the oldest US Senator?
There are a number of factors that result in incumbent US Senators winning reelection every six-years. Since 1964, 80 percent of them have seen off challengers to return to Washington DC for another term. This means that some have managed to keep their jobs well into their golden years.
The oldest serving US Senator ever upon leaving office was Strom Thurmond. At the ripe age of 100, he had been the longest-serving US Senator at that time but has now slipped to fourth place. The Dixie-crat turned Republican over the Democratic Party’s Civil Rights program in 1956 became a prominent leader of a more conservative GOP. He passed away a few months after retiring.
Currently Democratic Senator Dianne Feinstein beats out Senator Grassley as the oldest sitting US Senator by just under three months, both are currently 89 years old. While Senator Grassley is up for reelection in 2022, Senator Feinstein will be on the ballot in 2024. She won a special election in 1992 to become the senior Senator for California.