William Jacob Sanborn was born on September 5, 1853, in Keokuk, Iowa, to John E. Sanborn and Rebecca M. Tate. His father was a physician who owned $2,000 of real estate and $1,900 of personal property by 1860. His father was a surgeon in the Union army during the Civil War. The family lived in Taylor, Iowa, until the 1860s, when they moved to Rockport, Massachusetts. By 1910, Sanborn was working as a salesman in Cleveland, Ohio. He married Mary Firmin on March 27, 1914. They moved to Mount Dora, Florida, in the 1920s, and by 1930, they owned a house valued at $7,000. He died in 1941.