When Mansfield Tanner Lewis was born on 8 March 1844, in Missouri, United States, his father, Willis Lewis, was 49 and his mother, Emily McDowell, was 42. He married Nancy A. Burks on 15 May 1864, in Boone, Missouri, United States. They were the parents of at least 2 sons and 2 daughters. He lived in Perche, Boone, Missouri, United States in 1880 and Perche Township, Boone, Missouri, United States in 1900. He died on 14 December 1908, in Columbia, Boone, Missouri, United States, at the age of 64, and was buried in Boone, Missouri, United States.