Knauss apparently died of natural causes at about 3 p.m., two days before the start of 2000, said Marcella Moyer Schick, executive director of the Pheobe-Devitt Homes Foundation.
"She died quietly in her room. She was not ill," she said. "They had stopped in to see her just less than an hour before, and when the nurse went back, she had passed away."
Knauss, who was born Sept. 24, 1880, and lived a quiet life as a homemaker and insurance office manager, found herself in the international spotlight after the Guinness Book of Records declared her the world's oldest person in 1998 upon the death of Marie-Louise Febronie Meilleur of Quebec, who was 117.
"Sarah was an elegant lady and worthy of all the honor and adulation she has received," said Joseph Hess, an administrator at the nursing home.
Knauss, born in the coal town of Hollywood, Pa., lived through seven U.S. wars, the sinking of the Titanic and Charles Lindbergh's solo flight across the Atlantic.
She was older than the Brooklyn Bridge and was born before the dedication of the Statute of Liberty. She was 28 when Henry Ford introduced the Model T and 88 when Neil Armstrong walked on the moon in July 1969.
When asked in a 1995 interview if she enjoyed her longevity, Knauss said: "I enjoy it because I have my health and I can do things."
Her daughter, Kathryn Sullivan, 96, of Allentown, described her in a 1988 interview as a tranquil person who nothing could faze.
"That's why she's living this long," Ms. Sullivan said.
Knauss is survived by her daughter, several grandchildren, great-grandchildren and great-great-grandchildren.