She had fought "a long battle" with Alzheimer's disease, it said.
"I have lost my mother, my mentor and my best friend," Jeanne Phillips said in the statement.
"My mother leaves very big high heels to fill with a legacy of compassion, commitment and positive social change. I will honor her memory every day by continuing this legacy."
Phillips, born Pauline Esther Friedman, was the twin sister of Esther Pauline Friedman, better known as the equally famous agony aunt Ann Landers. She died in 2002 after she was diagnosed with cancer.
Their hometown was Sioux Falls, Iowa and -- rather aptly for a pair who would be American pop culture icons -- their date of birth was the Fourth of July, 1918.
While Ann Landers broke into print in Chicago, Dear Abby got her start in San Francisco by pestering the editor of the Chronicle with an offer to write a better advice column than the one the daily newspaper had been running.
A happily married suburban housewife and mother of two teenagers, Phillips had never made a living by writing, but she reckoned she could bash out a regular column given how people had always gone to her with their woes.
During the tumultuous 1960s and 1970s, Phillips used Dear Abby to champion equal rights for women, minorities and those with mental illness and physical disabilities, Universal Uclick recalled.
But in a 1989 anthology, she credited her Russian Jewish heritage -- her parents had come to America as impoverished immigrants -- for her trademark one-line wisecrack responses to some of her readers' most perplexing problems.
"My humor tends to have a sharp edge, a touch of healthy sarcasm and I frequently answer a question with another question," she explained in a 1989 anthology of her best columns.
Phillips kept getting hundreds of letters from readers every day well into her 70s. "Age has nothing to do with it," she once said. "It's only work if you would rather be doing something else."
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