Sen. Edward M. Kennedy, the senior Senator from Massachusetts whose broad vowels were synonymous with Boston and whose liberal legislative record towered over all others, died late Tuesday night at his home in Hyannisport after a 14-month battle with brain cancer. He was 77 and had served in the U.S. Senate for 46 years. And he had long been a familiar presence on the Vineyard, where he is both credited for the infamy of Chappaquiddick and for the pioneering federal land trust bill that ultimately led to the creation of the Martha’s Vineyard Commission.

In both instances, Ted Kennedy, as he was known, had a profound impact on the Vineyard.

“The changes that are basically irreversible are the ones that come from ill-planned development,” he told the Vineyard Gazette in a 1986 interview.

Flags flew at half-mast on the Vineyard and in the nation’s capitol on Wednesday following the death of the senator who was hailed as the last lion. President Obama, who is vacationing on the Island this week with his family, took the podium in a field at Blue Heron Farm in Chilmark and addressed a small gathering of reporters. “He became not only one of the greatest senators of our time, but one of the most accomplished Americans ever to serve our democracy,” Mr. Obama said.

Senator Kennedy endorsed Mr. Obama during the presidential primaries in January of 2008, in what is now widely acknowledged as a turning point in the election. “He will be a president who refuses to be trapped in the patterns of the past,” he said during a rally for Mr. Obama.

Mr. Obama will deliver a eulogy at Senator Kennedy’s funeral in Boston on Saturday. Interment will be in Arlington National Cemetery, next to Mr. Kennedy’s brothers.

Edward Moore Kennedy was born on Feb. 22, 1932, in Brookline, the son of Joseph P. and Rose Fitzgerald Kennedy and the youngest of nine children in a prominent, wealthy Irish Catholic family deeply involved in the Democratic politics of Boston. Joe Kennedy, who had been a successful businessman, served in the Franklin D. Roosevelt administration, first as chairman of the Securities and Exchange Commission and later as ambassador to Great Britain.

The family owned homes in Boston, New York, London and Palm Beach, Fla., and young Ted had an unsettled childhood, attending 10 preparatory schools before finally finishing at Milton Academy.

“One thing which surprised me was how lonely his childhood was,” said Peter Cannellos, who edited Last Lion, a biography of Mr. Kennedy published by the Boston Globe this year, in an interview with the Gazette this summer.

Ted enrolled at Harvard, following in the footsteps of his brothers and father, but he was undistinguished as a student and was forced to leave the university after a cheating incident. The Korean War was on and he was eligible for the draft; he enlisted in the Army and served two years. He was discharged in 1953 with the rank of private first class.

He re-enrolled at Harvard and was more serious about his studies, majoring in government, playing football and excelling in public speaking. He graduated in 1956 and obtained a law degree from the University of Virginia Law School in 1959. He was admitted to the Massachusetts bar. In 1958 he married Virginia Joan Bennett, a debutante from Bronxville, N.Y. They had three children.

When John Kennedy was elected to the White House in 1960, the Senate seat was left vacant. Brother Robert Kennedy had already taken the post of attorney general. At 28, Ted was two years shy of the minimum age required to be a senator; a Kennedy family friend named Benjamin Smith 2nd took the seat until 1962, when Ted ran and won after a bitter, hard-fought contest against state Attorney General Edward McCormack.

So much of the rest of his story has been well told — the assassinations of John and Robert Kennedy five years apart, the plane crash in Westfield where he broke his back, the bone cancer that struck his son and cost him a leg, his divorce, his womanizing, his drinking, his bid for the presidency that failed almost as soon as it began, and much later, his second marriage and a final turn toward stability in his personal life, and the tragic death of his nephew John F. Kennedy Jr. in a plane crash off the Vineyard.

So much tragedy in one life, a good deal of it connected to the Vineyard.

And none more so than the incident at the Dike Bridge on the night of July 18, 1969 when Mr. Kennedy, who had been at a party with other legislative aides that night at a small house known as the Lawrence Cottage, drove his car off the narrow wooden bridge that divides Cape Pogue and Poucha Ponds and leads to a remote barrier beach on Chappaquiddick. Mary Jo Kopechne, a young legislative aide who was in the car with Mr. Kennedy, drowned. To this day no one knows what really happened that night, although the theories have filled books and piqued storytellers and investigative journalists across the world, owing in part to the Kennedy family mystique. Here is what is known: Miss Kopechne died and Mr. Kennedy did not report the incident for 10 hours. He was later convicted of leaving the scene of an accident. The incident drew the national press and put Chappaquiddick and the Vineyard squarely on the map.

“The story of the accident has grown into the story of getting the Story,” the Gazette reported a few days after the incident. “Never on the Island has a single incident been the inspiration of so many individual investigations. The digging by reporters continues, with more and more reporters arriving, representing papers and magazines not just from the Eastern Seaboard . . . .”

Forty years later the international intrigue over Chappaquiddick has died to a mere wisp of interest; when the anniversary passed this year there were scant stories in the national print press, and no visiting journalists appeared at the Chappaquiddick Ferry looking for the Dike Bridge (long since replaced). A generation has passed.

And what remains is Ted Kennedy’s lasting legacy in his work as a longtime ranking Senator: on voting rights and housing initiatives, on civil rights, including for Americans with disabilities, on education and of course on health care. “Though his personal life was a mess until his remarriage in the early 1990s, he never failed to show up prepared for a committee hearing or a floor debate,” wrote John M. Broder in The New York Times this week.

“He was the youngest child of a famous family, but his legacy derived from quiet subcommittee meetings, conference reports and markup sessions. The result of his efforts meant hospital care for a grandmother, a federal loan for a working college student, or a better wage for a dishwasher,” wrote Martin F. Nolan in The Boston Globe.

And while he was a Democrat in every sense of the word, his trademark was also his ability to work across the party aisle. Sen. Orrin M. Hatch, a Republican who worked with Mr. Kennedy, remarked about this on National Public Radio on Wednesday.

On the Vineyard Mr. Kennedy’s strongest legacy lies in the Martha’s Vineyard Commission, the unique regional land and water commission that was created in 1976 by an act of the state legislature. The origins of the state bill can be traced to the Nantucket Sound Islands Trust bill, pioneering federal legislation aimed at turning the two Islands into a national land trust, much like the Cape Cod National Seashore.

Mr. Kennedy introduced the trust bill in 1972; it was quickly dubbed the Kennedy Bill, and reaction was incendiary.

“It was as if Senator Kennedy had pushed the plunger on a remote control bomb. Martha’s Vineyard exploded,” wrote Ruth Mehrtens Galvin in a story in Blair and Ketchum’s Country Journal in 1977. “For five years the fight has gone on, encompassing sidewalk arguments and heated living room discussions, endless meetings, countless amendments, visits to the Islands by various senators and the governor, by delegations from the House of Representatives and the Department of the Interior.”

In the end the bill failed. Meanwhile, Massachusetts Gov. Frank Sargent stepped in with a compromise: a state bill to create the Martha’s Vineyard Commission, a regulatory commission considered unique in government, both then and now.

“I think in hindsight the [trust bill] could have been a tool to manage development,” Mr. Kennedy told the Gazette in an interview on the 25th anniversary of the bill. “But some good did come of it all.”

And at no time was Senator Kennedy more a Kennedy than when he was sailing.

“It always seemed that my brothers and sisters wanted to come here when the wind was the strongest and the waves were the largest and the boat was the wettest. As so many childhood memories, those remain emblazoned in my mind,” he told the Gazette in the 1986 interview.

He bought his two-masted Concordia schooner Mya, which he sailed frequently in waters around the Vineyard, from Matthew Stackpole on the Island.

His longtime friend Rose Styron recalled summers with Kennedys in every cormer of the Styron home on Vineyard Haven harbor.

“Every year Teddy would sail over with all of his children and Bobby’s children; they would all bring sleeping bags and sleep on the lawn,” she recalled. “And Teddy would always be up bright and early fixing scrambled eggs for the whole crew, with me as his sous chef. After that we would all pile into cars and go to a beach up-Island. Twice we were kicked off beaches — once by Tony Lewis’s ex-wife,” she laughed.

“There were just a million little adventures, but my serious life with Teddy was in Washington . . . . He got me safely out of Chile when I was there with Amnesty International [in 1974] and I was in trouble.

“And I remember after Chappaquiddick — when everything was a disaster. A few days after the accident Bill and I drove into the driveway and there was Teddy. He was just standing there because he knew we would welcome him.”

He is survived by his wife Victoria (Vicki) Reggie, three children, two stepchildren, four grandchildren and a sister. His niece Caroline Kennedy has a summer home in Aquinnah.

Mr. Kennedy will be driven by motorcade from Hyannisport to the John F. Kennedy Library in Boston on Thursday, where he will lie in repose. A funeral mass is planned for Saturday at Our Lady of Perpetual Help Bassilica in Roxbury.