The papers also include the diary kept by Billon on his travels from Philadelphia, Pennsylvania, to St. Louis in 1818; notes on outstanding citizens and events of St. Louis, from a village in the early territorial days to the latter part of the nineteenth century; two memoranda books containing Billon's original notes of early marriage, baptismal, and burial records; notes on Benito Vasquez and Joseph Motard; maps, plats, and additions of the town of St. Louis; early wills and documents; and material on the origin of St. Charles County, Missouri, the families of Vincennes, Indiana, and the transfer of Louisiana. Names of prominent citizens represented in the collection include William H. Ashley; Joseph Chauvin; the Chouteau family; Daniel P. Cook; Ninian Edwards; Charles Gratiot; Pierre Laclede Liguest; Peter Menard, Sr.; Joseph M. Papin; Dr. Saugrain; and General James Wilkinson. The collection also includes Billon's record book of orders for his 1894 book Territorial Annals of St. Louis in the American Days, which is notable for containing autographs of several prominent St. Louisans, and preservation copies of Billon’s memoranda and his Territorial Annals of St. Louis in the American Days.