When William Jennings Duncan was born on 30 August 1844, in Andrew, Missouri, United States, his father, Charles Duncan, was 38 and his mother, Dorcas Coffman, was 27. He married Mary Elizabeth Corell on 11 March 1875, in Henderson, Illinois, United States. They were the parents of at least 2 sons and 3 daughters. He lived in Walla Walla, Washington, United States in 1880 and Salem Election Precinct, Edwards, Illinois, United States for about 30 years. He died on 11 March 1929, in Waitsburg, Walla Walla, Washington, United States, at the age of 84, and was buried in Waitsburg, Walla Walla, Washington, United States.