What about Senators who died within the next term after not running again?
Arlen Specter was 82.
Jesse Helms was 87.
-PJ
Inoyue was his generation's Carl Hayden. Hayden represented Arizona in Washington from statehood in 1912 until 1969, 57 years to Inoyue's 53. Strom Thurmond (served to 100) was his generation's T.F. Green, who represented Rhode Island until he was 94 and lived to be 98.
Why do Senators keep getting reelected? It used to be seniority. The seniority system has been weakened, but I guess it still is. Stay in long enough and there's a lot of favors you can call in, and that helps for constituent services.
I guess you also become an institution or a symbol if you're around long enough -- or maybe people are just too passive and uninterested to vote you out, or they figure that if you're feeble enough you won't do any harm.
Thurmond died at 101, a little over a year after not seeking reelection.
Specter did seek reelection; he merely lost the primary.