Lum Cotton was born in Alabama in 1840. He and his father Giles Cotton were slaves on the Stroud Plantation. After becoming freemen, Giles moved into Robertson County where he became a Texas State Legislator for that county. He was also a teamster hauling supplies from Galveston to the Limestone County area.
Lum Cotton married Hagar Connor. In the 1870 Limestone County census, Lum is listed as a blacksmith, and he and Hagar have two children. In the 1880 census, the family is living in Precinct 5. Lum is listed as a farmer, and the couple have six children. In the 1900 census, the couple is farming land in Precinct 1. Lum died on June 10, 1900 and is buried in the Dancer Cemetery.