He was the son of Roswell King, the founder of Roswell, GA. He married twice. 1. Isabella Gibbs (AMW's cousin), by whom he had one child, Ida Bayard; the latter married her second cousin and son of AMW, William McNeill Whistler. 2. Mildred ('Millie') M. Bronaugh.
He went into the finance business in New York, and became a successful broker. He handled AMW's financial affairs in the early 1850s. He retired in Georgetown, Washington, DC.