The materials in this collection of James Birnie's papers date mainly from 1845-1864 and relate primarily to his business ventures and real estate holdings in Cathlamet, Washington. Materials in Series 1, Financial statements, include tax statements, accounts, and a ledger, which covers a five-year period and provides detailed documentation of Birnie’s investments. Also included is an extensive collection of bills and receipts related to Birnie’s store.

Series 2, Correspondence, includes justice of the peace verifications and real estate manuscripts, as well as correspondence related to construction of a wharf in Cathlamet.

Series 3, Vendors, contains various documents from vendors to the Cathlamet store. These include the Hudson's Bay Co., Leonard & Green, and Allan, Lowe & Co. of San Francisco. Documents in this series include invoices, financial statements, letters regarding receipt of goods, and letters regarding shipments and payments. The letters from Allan, Lowe & Co. provide details of shipping and commerce between San Francisco and the Columbia River area.

Series 4, Bound volumes, consists primarily of accounts, but also includes Birnie's letterpress copy book, which contains copies of his outgoing correspondence from 1853 to 1858. Also in this series are two volumes detailing transactions of the estate of James Scarborough, including expenses for Scarborough's sons.