Gertrude was born and grew up in Connecticut, and from a very early age dreamed of becoming an author. When she was nine years old she wrote her first “novel”, an imitation of Florence Kate Upton’s Golliwog stories, titled Golliwog at the Zoo.
Because of her frequent illnesses, Gertrude never finished high school, but in 1918, while she was teaching Sunday School, she was called to teach first grade, mainly because male teachers were being called to serve in World War I. She continued to write on her Boxcar Children series when she retired from being a teacher.
As well as her books in The Boxcar Children series, Warner wrote many other books for children, including The World in a Barn (1927), Windows into Alaska (1928), The World on a Farm (1931) and Peter Piper, Missionary Parakeet (1967). She also wrote some books for adult readers.
In her later life, before she died at age 89, Warner became a volunteer for the American Red Cross, the Connecticut Cancer Society and other charitable organizations.
The Boxcar Children Museum in Putnam, Connecticut is dedicated to Warner’s life and work, where many items from her life are exhibited, including the desk at which shoe wrote her first story titled Golliwog at the Zoo when she was 9 years old.