The collection consists primarily of typescript [carbon] translations of official communications among individuals involved in the government of Louisiana during the Spanish Period, 1763-1804. Two typed letters signed from Joseph Wheless, St. Louis attorney, and two typed letters, one signed, from Pierre Chouteau (1849-1910), St. Louis businessman, to W. B. Douglas, President, Missouri Historical Society, explaining the source, extent, and translation of the Archive, constitute the only original documents in the collection.
The core of the collection, ca. 160 items, is made up of items to or from Carlos Dehault de Lassus, 1764-1842, last Spanish governor of Upper Louisiana, 1799-1804. Other individuals represented in the collection include Andreas Lopez de Armesto, Santiago de Arvaiy, Manuel Arzaro, Miguel José de Azanza, J. Bruff, Basil Brusierre, Francisco Buriony, the Baron de Carondelet, the Marquis de Casa-Calvo, Pedro Ceballos, Pierre Chouteau (1758-1849), Santiago Clamorgan, Benjamin Fooy, Diego de Gardoqui, Manuel Gayoso de Lemos, Juan Goutier, Carlos de Grand-Pré, Agustin Grande, the Marquis de la Hormasas, Carlos Howard, Manuel Lisa, Regis de Loisel, Ramon de Lopez Y Angulo, Esteban Miró, the Count de Montarco, Juan Ventura Morales, Manuel Gomez Moro, the Principe de la Paz, Thomas Portell, Francisco Rendón, Francisco Riu, Pedro Rousseau, Manuel de Salcedo, G. C. Sibley, John Sparks, Bartolomé Tradiveau, Cenon Trudeau, Antonio de Ulloa, Cayetano Valdes, Louis Viviat.
Subjects considered at some length, aside from day-to-day governmental functions, include relations with the United States and with the Native Americans, trade regulations, and the geography of the area. Of particular note are Lassus’ Diary on Evacuation at the time of surrender to the United States, 1804-1805; an early account of the Lewis and Clark Expedition; a description of St. Louis in 1812; and the Articles of Association of the Missouri Fur Company dated January 24, 1812.