The materials in this collection relate to J. O. Simmons' family and work from the late 1830s to 1880s. The collection documents agricultural and mercantile exchanges on the Mississippi River during and after the American Civil War, the employment of African American and immigrant laborers during the early Reconstruction era, and land dispute issues among white settlers in the Territory of Dakota in the 1870s. The collection contains correspondence; ephemera (circulars, pamphlets, and broadsides); financial documents, such as account books, bills, invoices, and receipts; and legal documents, including but not limited to, quit claims, deeds, permits, contracts, agreements, licenses, affidavits, petitions, and court statements and testimonies. There are also some of Simmons' personal writings, which include a few lines of verse and several essays on his politics. The bulk of the collection is the correspondence that spans the 1840s to 1880s, and which cover the span of Simmons' life, beginning in Ohio.