Original manuscripts, 1793-1818, 1823. Most numerous and significant are the records of the intended French expedition against Louisiana proposed and organized by Clark in 1793. Opening the volume is a draft of Clark's proposal in the handwriting of James O'Fallon, dated in February 1793, and addressed to the French minister [Edmond Genet]. Also found are: John Brown's letter of introduction of André Michaux, the French botanist who was also deeply involved in the French project; three letters written by Michaux; letters offering their services written by Clark's friends and former officers, Benjamin Logan and John Montgomery; and a letter from Governor Isaac Shelby of Kentucky to Secretary of State Thomas Jefferson, endorsed by James Monroe, discussing the legality of the expedition. Nearly a dozen letters, 1794-1796, by Samuel Fulton, Clark's agent in the United States and France, concern first provisions and supplies and later the lengthy negotiations with the French government for payment of the expenses incurred by Clark and his men. Other papers pertaining to the French plan include: an extensive printed broadside (December 13, 1793) on the navigation of the Mississippi composed of an address by John Breckenridge “To the INHABITANTS of the UNITED STATES West of the Allegany and, Apalachian [sic] Mountains;” Clark's letter (1795) to the Committee of Public Safety requesting renewal of the expedition; single letters by Joseph Fauchet, French minister to the United States in 1794, Hugh McCullom, and P. Tardiveau; and the detailed financial accounts and claims submitted to the French government.

Nearly a dozen letters, 1794-1810, by Jonathan Clark relate primarily to his unsuccessful efforts to gather proof and secure payment of his younger brother's claims against the state of Virginia, but there are also references to law suits, family affairs, and national events and economic conditions. There are also numerous personal letters from other members of Clark's family; his brothers Edmund and William; and his relatives in the Croghan, Gwathmey, and O'Fallon families. Between 1798 and 1806 there are letters from three authors, Joseph H. Daviess, Allan B. Magruder, and Stephen C. Ustick, requesting use of Clark's papers for their writings on western history and Indian warfare. Inspired by news of a Fourth of July tribute to Clark by citizens of Jefferson County, Kentucky, in 1811, Francis Vigo also sent felicitations to his old friend. Letters by William Croghan, Charles Fenton Mercer, and John Pope detail the award of a sword and pension to Clark by Virginia in 1812, and Clark's gracious acceptance. Receipts, 1809-1813, for services of doctors Richard W. Ferguson and John Collins and a few of the family letters allude to the amputation of Clark's leg and other health matters. One letter (1823) by Silas Moor Stilwell concerning the land grant to the Illinois Regiment was addressed to William Croghan after Clark's death.

Other correspondents not previously mentioned include: John Adair, Abraham Buford, Abraham Chapline, Dennis Fitzhugh, Samuel F. Fitzhugh, George C. Gwathmey, Owen Gwathmey, Samuel Gwahmey, Benjamin Howard, Harry Innes, John O'Fallon, G.D. Pendleton, Worden Pope, Samuel Shannon, and William Sullivan. Also found are a few Clark obituaries and a copy of John Rowan's address at the funeral. Similar materials are also in Volume 12 J. Filed as an undated paper is a printed piece, “An Act to Incorporate the Indiana Canal Company” [1811], in which Clark was listed as one of the directors.