Mary Jane Kerr was born on April 8, 1850, in Titusville, Pennsylvania, to Andrew and Mary Kerr. Her father was a farmer who owned $2,000 of real estate and $500 of personal property by 1860. She grew up and attended school in Oil Creek, Pennsylvania, and she married Civil War veteran David Mack in the mid-1860s.
They lived in Cherrytree, Pennsylvania, and her husband worked as a farmer. By 1870, they owned $700 of personal property. They moved to West Wheatfield, Pennsylvania, in the 1870s. Her husband died on April 21, 1921. She applied for a widow’s pension in June 1921 and eventually secured one. She died of “carcinoma of [the] liver and stomach” in Dravosburg, Pennsylvania, on November 16, 1935.