More than 60 personal letters still survive, including several that contain expressions of the most intimate kind. Unfortunately, we can read only one side of the correspondence (letters from King to Buchanan). One popular misconception holds about that their nieces destroyed their uncles letters by pre-arrangement, but the real reasons for the mismatch stem from multiple factors: for one, the King family plantation was raided during the Battle of Selma in 1865, and for another, flooding of the Selma River likely destroyed portions of Kings papers prior to their deposit at the Alabama Department of Archives and History. Finally, King dutifully followed Buchanans instructions and destroyed numerous letters marked private or confidential. The end result is that relatively few letters of any kind survive in the various papers of William Rufus King, and even fewer have ever been prepared for publication.
By contrast, Buchanan kept nearly every letter which he ever received, carefully docketing the date of his response on the backside of his correspondence. After his death, Johnston took charge of her uncles papers and supported the publication of a two-volume set in the 1880s and another, more extensive 12-volume edition in the early 1900s. Such private efforts were vital to securing the historical legacy of U.S. presidents in the era before they received official library designation from the National Archives.