The Horatio Seymour papers are concerned chiefly with land holdings and business dealings of the Seymour family, and the related Bleecker and Tibbits families. The collection is comprised of financial accounts, legal agreements, and commercial correspondence. Topics include the development of business in the city of Utica, milling, banking, and iron manufacturing. Other topics include the Saint Mary's Ship Canal and connecting Lake Superior with the lower Great Lakes.

Oversize indentures relocated from Box 1 and Box 2. Also includes a July 3, 1871 edition of The Argus newspaper.