Sallie was born in August 30, 1863 at Boscobel plantation to John Randolph Lacy and Emma Prothro of St. Maurice Plantation on the Red River.
She was educated under Thomas Owen Benton at the Ouachita Female Academy.
Sallie married Robert Francis Humble, a civil engineer and planter December 11, 1890. They had four children: Robert F., Sallie, John T., and Mary.
She served as a fourth grade teacher at the Monroe City Schools from 1902 to 1937.
She died February 22, 1957 and is buried in Riverview Cemetery.
Sallie Humble Elementary School is named for her.