The oldest living person in the US has died aged 115. Here are 6 things that may have helped her stay healthy so long.

• Elizabeth Francis, the oldest living American, has died aged 115.
• She attributed her longevity to God.
• Her family put her longevity down to her cooking from scratch, being close to family, and not smoking.

In 1909, William Taft replaced Theodore Roosevelt as president of the US, women couldn't yet vote in the US, and Elizabeth Francis — who was until recently the oldest living American — was born.

Francis claimed the title in February, and was also the third oldest person in the world. She died at home on Tuesday, surrounded by family, her granddaughter, Ethel Harrison, 69, told ABC news on Wednesday.

"She loved the Lord. Her faith was extremely strong," Harrison told ABC News. "She was always jolly, you know, 'how you doing? You're doing okay?' That was just her personality.

"And she would always say treat people like you want to be treated. And that was her motto."

Francis was born in Louisiana but moved to Texas in 1920. She lived with her 95-year-old daughter, Dorothy Williams, from 1999, where caregivers visited daily, Today reported last summer.

She started using a wheelchair in 2017, at the age of 108, The Washington Post reported, and was bedbound when the outlet interviewed her in August last year.

Francis also had some memory problems in her last years, but she was mentally alert and recognized her family, Williams told Today. When researchers from LongeviQuest, an organization that verifies the ages of supercentenarians, visited her for her 114th birthday in July last year, she was able to hold court with visitors for four hours.

While Francis didn't have a secret for living to 115, she credited her longevity to God. She told Today last year: "It's not my secret. It's the good Lord's good blessing. I just thank God I'm here."

Her family shared the lifestyle factors they think contributed to her living so long.

Francis walked regularly and never smoked or drank alcohol

Francis always tried to take care of her health, including by walking regularly until her 90s and never smoking or drinking alcohol, Ethel Harrison, her granddaughter, told Today.

She always cooked using vegetables that she grew in her garden, such as collard greens, mustard greens, carrots, and okra, according to Today.

Harrison told ABC13 that she never saw her grandmother eat fast food.

"Whenever you went to her house, I don't care what day of the week, she was cooking. So I just think that had a lot to do with it," she said of her grandmother's longevity.

Dietitians typically recommend people center their diets around whole foods, with one study suggesting that eating more plants and less processed food could add a decade to a person's life.

Francis also spent a lot of time with her family: Harrison visited her mother and grandmother at their house most days, and she told Today that they were "always doing things together as a family unit."

Research suggests having strong relationships and socializing are associated with a longer, healthier life.

Francis also worked hard to support her family as a single mother and stayed active even when she retired. "She was a hard worker. That's what I remember most about her. Even when she retired, she still would work. She did domestic work, but she was always working," Harrison said.

LongeviQuest researchers previously told Business Insider that working for as long as possible was common among the supercentenarians they'd met, while a 2016 study found that retiring early increased the risk of death.