Uncle Nelson was vice president. Uncle Winthrop a governor. Great-grandfather Nelson a senator.

Political bloodlines, he had.

But the great American electoral dynasty that abruptly announced its end Friday, or at least signaled what looks to be a long, long pause, always evoked more. That name on the ballot — Rockefeller — meant money. It meant epic-scale success. It meant everything.

And it meant that Jay Rockefeller wasn’t ever going to be just some Democratic senator from West Virginia. Rockefeller, who said Friday that he would not seek reelection in 2014 after nearly three decades in the Senate, was always going to be the oil titan John D. Rockefeller’s great-grandson, too. One of the heirs to a legendary fortune.

“He’s proud of being a Rockefeller. He talks about his uncles and his grandfather, about that legacy. It’s an important part of who he is and how he thinks about himself,” Rockefeller’s longtime political adviser, Geoff Garin, said in an interview. “He found a way to be a Rockefeller that was about serving people.”

Dynasties like these roll across American political history. Not just Rockefellers, but Adamses and Kennedys and Bushes. A nation formed to escape power granted as a birthright still embraces power that follows the contours of a family tree. Voters even expect it, and so do political scions.

“It’s so predictable!” said Stephen Hess, a Brookings Institution senior fellow emeritus and author of the book “America’s Political Dynasties.” “It’s daddy’s business and increasingly it’ll be mommy’s business, too.”

For Hess, each dynasty takes on a different aura. There were the “crafty” Roosevelts, headlined by a couple of presidents — Franklin Delano and Theodore — and his favorites, the Tafts, whose standout, William Howard, was about the “nicest” guy ever to occupy the Oval Office, in Hess’s estimation, and who also managed to become chief justice of the Supreme Court.

The Rockefellers were almost incidental dynasty builders, Hess said. “That generation — the robber barons, if you want to call them that — wasn’t interested in politics. Politics was something you could marry into.”

Indeed, John D. Rockefeller’s only son married the daughter of Nelson Aldrich, a prominent Republican senator of the late 1800s and early 1900s who wielded tremendous influence over monetary policies. Their son, Nelson Aldrich Rockefeller, became governor of New York and was Gerald R. Ford’s vice president. Another son, Winthrop Rockefeller, became governor of Arkansas.

“My great-grandfather, John D. Rockefeller, worked at it very, very hard. There’s an ethic in the Rockefeller family of hard work,” Jay Rockefeller wrote in an e-mail late Friday. “It’s expected that everybody work hard. And there has been a tradition of public service.”

John D. “Jay” Rockefeller IV entered politics unconventionally, drawn into that sphere by his experiences as a volunteer for VISTA (the precursor of Americorps) in Emmons, W.Va., a small coal mining town. “Coming to West Virginia was life-changing for him,” Garin said. “West Virginia exposed him to a whole new world that broadened his world; and in a lot of respects it gave his career a defining purpose.”

In the eyes of some, the newcomer who’d grown up in New York was “a carpetbagger,” said John Raese, a West Virginia businessman who lost a tight Senate race against Rockefeller in 1984. He tried to “save Appalachia,” Raese said mockingly.

Rockefeller won a seat in the West Virginia House of Delegates in 1966. He was elected secretary of state in 1968, but lost a campaign for governor in 1972. He ran again and won two terms before spending millions of his own money to finance his successful run for the Senate in 1984.

With a famous name came expectations, and many assumed he would someday seek his party’s presidential nomination — like his uncle Nelson, who made three failed attempts. In Washington, he struck colleagues with his mild manners. He was not a firebrand prone to windy speeches. In the halls, he was approachable. It wasn’t exactly what Washington expected.

In the Senate he became close friends with Sen. Edward M. Kennedy, two sons of famous families, each of whom had benefited from their legacies and carried their weights. In an interview Friday, Kennedy’s son, Patrick Kennedy — a former Democratic congressman from Rhode Island — recalled the sneering accusation of one of his father’s senatorial opponents, Eddie McCormack. If his father’s name had been Edward Moore instead of Edward Moore Kennedy, his candidacy “would be a joke,” McCormack said during the 1962 campaign.

But ultimately, a famous name is “an enormous help,” Patrick Kennedy said. “It gave me so much goodwill and credibility before I even had to stand on my own.”

For Rockefeller, standing on his own in the Senate meant crafting a reputation as a progressive champion of health care for the poor, an issue with particular resonance in his poverty-wracked state. He was the author of the Children’s Health Insurance Program, better known as CHIP, which provided coverage to 8 million children. He also was a leading supporter of President Obama’s sweeping 2010 health-care reforms.

“From his time in the state legislature to the governor’s office to the Senate floor, Jay has built an impressive legacy, one that can be found in the children who have better schools, the miners who have safer working conditions, the seniors who have retired with greater dignity, and the new industries that he helped bring to West Virginia,” Obama said in a statement Friday.

Few think that another Rockefeller will occupy an office on Capitol Hill in the foreseeable future. “I don’t think his own kids are interested in [elected] public service,” Garin said. “He’s got great kids and I think they’ll find other ways to serve.”

Still, Rockefeller, in his e-mail Friday, wasn’t ready to completely discount the possibility, saying his family’s future contributions “could mean public service, like me, or doing good work for the environment, health care and other important fields.”

Rockefeller made it all official Friday, but many in Washington began to suspect he might be eyeing the exit last summer. In June, he rose to argue against efforts to block the Obama administration’s targeting of emissions from coal-fired plants. He didn’t pound the podium while he criticized one of his state’s most powerful industries. That’s not his way. He didn’t shout.

But his words popped. A tall man with thinning hair, he stood hunched into the microphone and accused the coal industry of “scare tactics.”

“The dialogue on coal, its impact and federal government’s role has reached a stunningly fevered pitch — carefully orchestrated messages that strike fear into the hearts of West Virginians and feed uncertainty about coal’s future are the subject of millions of dollars of paid television ads, billboards, break room bulletin boards, public meetings, letters and lobbying campaigns,” he said.

It wasn’t the final, blazing cry of an expiring political dynasty. It was closer to a whisper that everyone could hear.