Thiers was born as Louisa Kirwan Capron in Whitesboro, New York on 2 October 1814 as the youngest of six children born to Seth and Eunice (née Mann) Capron, who were 52 and 47 respectively. Her father was a veteran of the Revolutionary War. She had four brothers and one sister. During her adulthood, she was an advocate for women’s emancipation.

In the 1830s, Thiers and her family moved to Wisconsin. She married David Bodine Tears – later changed to Thiers – in 1847, and the couple moved to Milwaukee in 1850. They had five children: Ella (who died in infancy), Herbert, Emma, Edward, and Louis. The family were living in Alton, Illinois in 1860, and Kenosha, Wisconsin in 1870. She was widowed in 1875.

In her 80s, Thiers moved in with her daughter Emma. As a centenarian, Thiers recollected the opening of the Erie Canal, which her cousin, Herbert Mann, officiated. She reminisced about travelling on canal boats, riding the first steam railway from Schenectady to Albany, and witnessing Halley’s Comet twice, in 1835 and 1910.

At the age 106, Thiers could still read and write letters by hand. She liked to keep abreast of current events. She attributed her longevity to a moderate diet, lots of sleep, exercise, having interests in life, and being happy, as well as making others happy. At the age of 111, she stated that “you can’t mix love and a career” and that “motherhood is one of the biggest blessings that can come to any woman”.

Thiers died in Milwaukee, Wisconsin on 17 February 1926 at the age of 111 years, 138 days. Her successor as the world’s oldest person was then-110-year-old Delina Filkins, who would go on to break her longevity record. One of Thiers’ great-granddaughters, Mary (Dorr) Hastie, died in 2016 aged 104.