Helen Admonia Robertson was a midwestern farm girl who lived in three centuries, witnessed some of the early flights of the Wright brothers and worked in a Washington bank until she was 86. When she died Oct. 6 of a stroke at Buckingham's Choice, an assisted living center in Adamstown, she was 106 years old.

Miss Robertson, who was born Dec. 29, 1898, when William McKinley was president, never married and never learned to drive. Yet through sheer longevity she led a life of almost epic scale, reflecting many of the technological and social changes that have marked the country's progress over the past century.

She was born near Logansport, Ind., and grew up on a series of farms, including one in Peru, Ind., where several regional circuses had their winter quarters. She recalled riding show horses and feeding exotic circus animals as a girl. Her family later lived near Xenia and Dayton, Ohio, where Miss Robertson saw the Wright brothers take to the air in their early flying machines.

By the time she was 9, she was working as a hired housekeeper and maid. At 14, she left home to live with the family of a minister of the German Reformed Church, with whom she stayed for nearly 50 years. She received a teaching certificate from what is now Indiana State University and attended Miami University in Oxford, Ohio.

She distinctly remembered hearing of the sinking of the Titanic in 1912, she told The Washington Post in 2002, and recalled an assembly convened by her college president, at which he announced that the United States had entered what became known as the First World War.

Miss Robertson taught in one-room schoolhouses in Ohio for seven years, walking more than two miles each way on country roads. She worked in a doctor's office in Fort Wayne, Ind., a bank and a post office. Musically inclined, she gave singing lessons.

Throughout her life, she lived by the lessons she learned as a girl who had to earn her way in the world: She arose early, canned the vegetables she grew in her garden, ate simply and saved her money.

"She was a very thrifty lady," said her niece, Carol Oliver of Reston.

In 1935, the Rev. John J. Tapy, the German Reformed minister, was named superintendent of the German Orphan Home, which operated in Southeast Washington from 1879 to 1965. (It moved to Upper Marlboro in 1965 before closing in 1979.)

Miss Robertson was approaching 40 when she came to Washington with the Tapy family. She worked at the orphanage for seven years, then became a teller at the credit union of the main D.C. post office on North Capitol Street, where she worked for 26 years. While there, she fell in love for the only time in her life, with one of her customers -- a married man who went overseas during World War II and died soon after returning from the war.

As she recalled the episode to The Post more than a half-century later, her eyes filled with tears at what she called the one regret of her life.

"I liked a man a lot I couldn't have," she said.

"She was really beautiful when she was young," her niece said. "She used to say she had lots of opportunities to get married, but she was too picky."

In 1961, Miss Robertson bought a cottage in the Westover section of Arlington County, where she lived alone for 43 years. After leaving the credit union in 1968, she worked part time for the post office, mailing commemorative first-day covers to stamp collectors. She later tabulated account information for Riggs Bank until her eyesight began to fail when she was 86.

Miss Robertson, who leaves no immediate survivors, commemorated the birthdays of neighborhood children with chocolate lollipops wrapped inside dollar bills. She was a member of St. Michael's Episcopal Church in Arlington.

She maintained a garden at her home until she was 103 and subsisted on a mostly vegetarian diet. She never drank alcohol until she was 75, but after that she developed a taste for whiskey sours.

Asked the secret to her long life, she said it was simple clean living.

"The family joked that it was because she never got married, never had kids and never learned to drive," her niece said. But Miss Robertson's sister was married five times and lived to be 98.

When she spoke to The Post in 2002, Miss Robertson wondered whether she would live long enough to see another season of lettuce, beans and peas in her garden.

"I'm not afraid of anything," she said. "You have to die sometime."

Helen A. Robertson said the secret to her long life was simple clean living.