Elba Cabrera, a beloved godmother of the Puerto Rican cultural diaspora in New York City and the last survivor of Las Tres Hermanas, three sisters who galvanized educational, social and arts programs in their community, died on May 10 in the Bronx. She was 90.

Her death, in a hospital, was confirmed by her son Paul Mondesire.

Migrating to East Harlem from Puerto Rico with her mother before she was 2, Ms. Cabrera was trained in high school as a secretary and bookkeeper. After graduation, through the retail workers union, she had jobs selling hosiery and shoes.

Hailing from a family steeped in public service, she earned a college degree in her 40s and emerged as a patron of the arts, helping to identify and nurture talented musicians, artists, photographers, sculptors, poets and writers.

“Elba opened the doors of opportunity to hundreds of artists, particularly Puerto Rican and Latino ones, through her institutional roles or through her personal networks,” said Félix V. Matos Rodríguez, the chancellor of the City University of New York and former president of Hostos Community College in the Bronx.

“In a world full of bitter rivalries and conflicting egos,” he added, “Elba provided a unifying voice and trusted ally that brought people together and got things done.”

The Puerto Rican Traveling Theater was among her beneficiaries. Its artistic director, Rosalba Rolon, recalled in an email: “Elba had a great eye for identifying the potential in many of us, to connect with our vision. On many occasions, she offered the key, literally, to her office so we could make copies of scripts, move chairs around and rehearse. She went beyond the call of duty. It is not always about money, which she offered often, but about helping to kick that door open.”

Her institutional roles and personal networks were manifold.

After graduating from SUNY Old Westbury on Long Island with a degree in political science in 1978, she was hired as associate director of the Association of Hispanic Artists, which promoted marginalized Latino artists through events, a newsletter, a directory and a weekly program on WNYC-TV.

After 1987, she became marketing director for the Lehman Center for the Performing Arts in the Bronx and the Hostos Community College Center for the Arts and Gallery; director of Hispanic affairs at the Center for the Media Arts in Manhattan; a consultant on membership with the Girl Scouts; and part of an Alzheimer’s outreach team for the New York City Department of the Aging.

Maria Elba Cabrera was born on Sept. 10, 1933, in Ponce, P.R., to Sixto Cabrera and Eva Cruz Lopez, a widow with two daughters. One of the sisters left for New York to live with an aunt on the day Elba was born.

The sisters reunited in New York in 1935. Elba’s mother worked in a hotel laundry and became involved with the Socialist Party. The family lived with their aunt, who worked in Mayor Fiorello La Guardia’s campaign. Their uncle was a dance promoter and welcomed many musicians to his home.

Elba’s sisters joined the Young Communist League. The eldest, Evelina López Antonetty, founded United Bronx Parents, a nonprofit that provides services for South Bronx residents, in 1965; she died in 1984. The middle sister, Lillian López, was among the first Puerto Rican public librarians in New York City and introduced Spanish language books into the library system. She died in 2005.

After graduating from Bronx Vocational High School (later Grace Dodge Career and Technical Education High School) in 1951, Ms. Cabrera met Anthony Mondesire at the Palladium Ballroom, in Manhattan’s theater district; they married in 1954. Mr. Mondesire died in 1996.

In addition to their son Paul, she is survived by another son, Tony Mondesire-Cabrera, and two granddaughters.

While working with United Bronx Parents from 1966 to 1978, Ms. Cabrera proofread for the filmmaker Amílcar Tirado, who was teaching at SUNY Old Westbury and encouraged her to enroll.

“She followed in the family tradition of service in the pursuit of better educational opportunities and social justice, while setting herself apart with her focused appreciation of the arts as a tool for the pursuit of happiness on every level,” Paul Cabrera said in an email. “And she did not believe in the notion that artists must starve.”

In 2015, when she was 81, Ms. Cabrera lamented the deaths of several Hispanic cultural figures who had made their reputations in the 1960s, linking Puerto Ricans in New York to their island roots while also creating new forms of expression. Among them were the poets Tato Laviera and Jack Agüeros and the photographer Frank Espada.

“My world is getting smaller because we’re losing so many people we admired, who were artists, activists and part of the growth of this city,” Ms. Cabrera told The New York Times. “I guess we were blessed to even know them. They had a vision of the world, and they also did it through their art. And that is their legacy. Not many of us can say that.”