Susan C. Fargo’s lengthy career in the Massachusetts Senate began not with a victory, but with the epiphany offered by her defeat in a three-candidate Democratic primary for state representative in 1994.

“She said that’s the best thing that could have happened to her,’’ her daughter, Amanda, recalled, “because it opened her eyes to the Senate.’’

Mrs. Fargo, who was 77 when she died Friday in her Lincoln home, never lost another election, serving eight consecutive Senate terms after first being elected in 1996.

In early 2012, when Mrs. Fargo announced she would not seek a ninth term, then-Senate President Therese Murray called her “a passionate and true leader on Beacon Hill’’ and “a powerful voice’’ for her district in Middlesex.

Early in Mrs. Fargo’s tenure, she sponsored a bill to create a buffer zone around abortion clinic entrances and driveways to protect women entering and leaving.

“The level of violence has increased,’’ she told the Globe in 1999, several months after Dr. Barnett Slepian, an abortion provider in upstate New York, was murdered inside his home by a gunman who shot through a window, and little more than four years after John Salvi killed two people in shootings at two Brookline clinics.

“This is not an abortion bill,’’ then-Senator Fargo said at the time. “This is a public safety bill.’’

A buffer-zone bill initially was approved in 2000, after the Senate sought an opinion from the state Supreme Court as to the constitutionality of creating a 25-foot area around clinics that was free of protesters.

The law went through a series of court challenges, and a reworked buffer-zone law was enacted in 2007, before being struck down in 2014 by the US Supreme Court. The justices said that it infringed on the free speech of protesters and that the state’s concerns could be addressed through other laws against harassment and intimidation.

Mrs. Fargo also was a sponsor and key supporter — and, briefly, a key holdout — for a bill that instituted a statewide ban on smoking in restaurants and bars.

Concerned about how a House-Senate compromise bill defined penalties and other parts of the proposed law, she changed her vote, which temporarily held up the measure in a deadlocked committee.

A few days and some word changes later, she pronounced it “a bill I am proud to endorse.’’ After she changed her vote to break the tie, the bill was passed and the ban went into effect in 2004.

“I do not support turning smokers into criminals, and I believe in protecting jobs,’’ she said after dropping her opposition. “Whenever a governmental authority has power to close a business and put people out of work, I think fairness requires a stand.’’

Mrs. Fargo “was remarkably successful in getting ideas formed into legislation, and then getting those bills actually signed into law,’’ said Don Siriani, her chief of staff during her entire Senate career.

Along with her Senate assignments, which included chairing the Energy Committee and the Joint Committee on Public Health, she formerly chaired the Caucus of Women Legislators.

“I never saw her pick a fight, political or otherwise. She made friends, but she never backed down on a bill,’’ Siriani said, referring to the changes she secured in the smoking ban for restaurants and bars.

The middle of three children, Susan Cooley was born on Aug. 27, 1942, in Peoria, Ill., and grew up in that central Illinois city.

Her father, Dr. William Cooley Jr., was an obstetrician-gynecologist. Her mother, Adelaide Nation, was an artist known for her word play.

Both of her parents were prominent in the community, and she sometimes referred to them as “the ‘Peoria shoulds’ – you should do this, you should do that, this is how you should behave,’’ said the former senator’s only child, Amanda Reed Fargo of Lincoln.

Though close to her family, Mrs. Fargo was eager to leave Peoria “because she wanted more – she had big dreams, big aspirations,’’ Amanda said.

After attending Stephens College in Columbia, Mo., for two years, she finished a bachelor’s degree in 1964 at Northwestern University, from which she graduated summa cum laude and Phi Beta Kappa and where she also was homecoming queen.

She graduated from Harvard University in 1965 with a master’s in teaching. Years later, she received a certificate in public leadership from the Harvard Kennedy School.

During her master’s work at Harvard, she met Foster M. Fargo Jr., a Harvard Business School student. They married in 1966.

“Their roommates were dating and set them up on a blind date,’’ Amanda said. “My mom said she met him and he was scary smart and really nice and very handsome.’’

An innovator in inkjet technology, Mr. Fargo was an electrical engineer who also had degrees from Yale University and the Massachusetts Institute of Technology. He died on April 14 of a cardiovascular problem.

After marrying, the Fargos lived in Cambridge and then in Newton, where she was a middle school teacher. The family subsequently moved to Lincoln, where she became editor of the weekly Lincoln Journal newspaper, organized a land-use conference, and served for six years on the Lincoln Board of Selectmen.

In 1996, she ran for the then-open Fifth Middlesex District Senate seat. (After redistricting, it became the Third District.)

Her candidacy drew the endorsement of the Globe’s editorial board, which noted that she had served “on the board of Emerson Hospital and the state’s low-level radioactive waste board, giving her real-world knowledge of health and environmental issues. She was a teacher in the Newton public schools and helped advance some rare affordable housing in Lincoln.’’

She won that race with nearly 53 percent of the vote in what would turn out to be her closest general election. In 2000, she received nearly 70 percent of the vote, and she garnered nearly 60 percent in 2004, when she was considerably outspent by John Thibault, her Republican opponent.

“Her motto around here with our staff was to ‘listen, learn, then lead,’ ’’ said Siriani, who is now legislative and communications director for Senate minority leader Bruce Tarr. “That’s the approach we took through her entire time in the Legislature.’’

Mrs. Fargo “was definitely ‘the nice lady from Lincoln,’ ’’ he added. “That’s how I thought of her. I have already started to miss her.’’

In addition to her daughter, Mrs. Fargo leaves her sister, Marcia Cooley Blevins of McMinnville, Ore.; her brother, William Carl Cooley of Concord, N.H.; and a grandson.

Family and friends will gather to celebrate Senator Fargo’s life and career at 3 p.m. Saturday in First Parish Church in Lincoln. A private burial will be held in Lincoln Cemetery.

Amanda had returned from Florida to live near and help out her parents in the years since her mother retired from the Senate.

“She was extremely bonded to my son, Brady. She would walk into the room and see him and smile from ear to ear,’’ Amanda said, adding that her mother, whose health had been declining, “loved so deeply. I feel like she died of a broken heart, ultimately, after my dad died.’’

Marquard can be reached at bryan.marquard@globe.com.