Correspondence relating primarily to the U.S. Post Office Dept.; Democratic Party; politics; legislation; patronage; the secession crisis of 1860-1861; King's literary, historical, and social activities; and social life in Washington, D.C., in the latter half of the 19th century. Correspondents include Adam Badeau, Chauncey F. Black, James Buchanan, Nahum Capen, Schuyler Colfax, Andrew Gregg Curtin, George Ticknor Curtis, J.C. Bancroft Davis, John A. Dix, William Maxwell Evarts, John W. Forney, Edward Miner Gallaudet, Hannibal Hamlin, William Harkness, Joseph R. Hawley, Joseph Holt, John James Ingalls, Harriet Lane Johnston, De B. Randolph Keim, George Kennan, Robert Todd Lincoln, Hugh McCulloch, Justin S. Morrill, Levi P. Morton, Crosby Stuart Noyes, Franklin Pierce, Benjamin Perley Poore, Fitz-John Porter, Daniel Edgar Sickles, Ainsworth Rand Spofford, John C. Spooner, Moses Coit Tyler, John Wanamaker, and Robert C. Winthrop. Also includes correspondence of his son, Horatio C. King, with Fitz-John Porter and Daniel Edgar Sickles.