When Sophus Alexander Fillerup was born on 10 July 1880, in Lakeview, Utah, Utah, United States, his father, Andrew Peter Fillerup, was 49 and his mother, Caroline Rasmussen, was 38. He married Barbara Isabell Fisken on 16 November 1908, in Butte, Silver Bow, Montana, United States. They were the parents of at least 1 son and 3 daughters. He lived in Spokane, Spokane, Washington, United States in 1935 and Metaline Election Precinct, Pend Oreille, Washington, United States in 1940. He died on 8 February 1963, in Tiger, Pend Oreille, Washington, United States, at the age of 82, and was buried in Fairmount Memorial Park, Spokane City, Spokane, Washington, United States.