John Hannibal Emerson was born in Jefferson County, Virginia, in 1807. His parents moved to Pike County, Missouri, when he was 11 years old. He later was employed in merchandising and was elected to the Missouri state legislature. He came to Iowa in 1841 and settled in Dubuque, and in 1850 was mayor of Dubuque. Mr. Emerson was a delegate in the 1857 Constitutional Convention in Iowa City. He was a real estate dealer. Mr. Emerson was a Democrat in politics.