The papers of the Nicholas King family span the years 1792-1987, with the bulk of material dating from 1792 to 1861. The journals, correspondence, notes, genealogies, visas, photographs, and drawings comprising the collection consist primarily of the papers of three members of the King family: Nicholas King (1771-1812), English-born engineer and surveyor of the city of Washington, D.C.; his son-in-law William Wade (1789-1875), United States Army ordnance officer and part owner of a series of steam engine and cannon foundries in Pittsburgh; and his grandson Nicholas King Wade (1823-1899), engineer and foundry owner. The papers are arranged alphabetically by name of family member. A small group of miscellany contains genealogies, photographs, and drawings. Oversize material is housed separately.

The papers of Nicholas King consist largely of a series of journals containing diary entries (some in shorthand), drawings, and treatises on a variety of subjects. The earliest volume, written in 1793 while traveling through Suffolk, East Anglia, and Yorkshire prior to his immigration to the United States, records his observations on agriculture, architecture, oak timber, tithing, and the poor. The second journal, begun in August 1794 when King was a resident of Philadelphia, contains an account of a trip from Philadelphia to Bethlehem, Pennsylvania; advice for immigrant settlers and American land speculators; and passing comments on American agriculture, racial attitudes, and Pennsylvania penal reform. A third journal records his work as a surveyor in Washington, D.C, from 1796 to 1799. A board of commissioners responsible for overseeing the construction of federal buildings and the sale of city lots hired King as a surveyor in 1796. Also included are transcribed excerpts from several journals which have since been lost. One of these recounts King's transatlantic crossing in 1793 and his earliest impressions of America. The transcripts include copies of letters from King and his father, Robert King, who was also an engineer and surveyor. The collection contains a small portrait of King, a sketch of St. John's Episcopal Church in Washington, D.C, and several photographs of family portraits.

The papers of William Wade relate primarily to his participation in an inspection tour of European cannon factories sponsored by the War Department in 1840. Included is a letter from Wade to his son Nicholas before his departure, two visas, and a transcribed memorandum by Wade concerning the trip. In a letter dated 1861, Mark A. Cooper of Georgia expressed interest in acquiring a machine used to test the strength of iron. The letter, written eight days after the attack on Fort Sumter, is annotated with Wade's refusal to assist him.

The papers of Nicholas King Wade consist of a series of letters to his sister, Elizabeth Stone Wade, describing his journey from Berlin, Germany, to St. Petersburg, where he had a contract with the Russian government to manufacture military ordnance.