Julie Campbell (1908-1999) was born in Flushing, New York, and she and her character, Mart Belden, had the same birthday. She traveled extensively as a child as the daughter of an Army officer. She won her first short story contest when she was eight years old, while living in Hawaii. Campbell married Charles Tatham Jr. in 1933, and the two collaborated on a number of magazine pieces and articles. Campbell began writing the Trixie Belden series while living in a restored farmhouse in the Hudson River Valley with her husband and two sons.

The series was set in the fictional town of Sleepyside, but it was based on Campbell's hometown in the Hudson River Valley near Ossining at the time. Campbell lived on Glendale Road, and her home, Wolf Hollow, was the inspiration for Crabapple Farm. Julie Campbell, who was 91 years old at the time of her death, died in 1999. She was still passionate and determined, just like Trixie, at the age of 91.