Dianne Feinstein and Barbara Boxer have been senators for nearly a generation — but they're not yet California's longest-serving senators. Both would need to run for a fifth full Senate term to dethrone Hiram Johnson. And the current runner-up is Alan Cranston, who served four six-year terms.
Term in Senate: 1917-1945
A progressive Republican, Johnson railed against railroad interests, which he believed had outsized influence in state government and the courts. As governor, he persuaded voters to legalize the recall of elected politicians and establish the referendum and ballot initiative. He signed the Alien Land Law in 1913 that prohibited noncitizens ineligible for citizenship from acquiring property in California, which historians say targeted immigrants from Japan. In the Senate, he was an isolationist and spoke against participating in World War I, saying the U.S. shouldn't help "a little group of unpronounceable races." He attempted a run for president in 1920, and turned down the vice presidential spot on the Warren G. Harding ticket. The man who ran with Harding instead, Calvin Coolidge, became president when Harding died in 1923.
Term in Senate: 1969-1993
A one-time foreign correspondent, Cranston was elected to the Senate in 1968, where he focused on nuclear arms control and disarmament, civil rights and the environment. He was elected seven times as the Democrats' No. 2 leader in the Senate, the party whip. He attempted a presidential bid in 1984. He was tarred by the scandal enveloping Charles H. Keating Jr., the Lincoln Savings & Loan operator accused of looting the Irvine-based institution and cheating elderly investors, and later reprimanded by a Senate ethics committee for "an impermissible pattern of conduct" with Keating. He declined to run for a fifth term in 1992, citing a prostate cancer diagnosis, as polls showed a likely loss.
Sources: U.S. Congress; Times archives; California Law Review; Online Archive of California