Frobisher's papers comprise a letterbook of the North-West Co. containing copies of letters written by Frobisher from April 1787 to October 1788, two original letters to Simon McTavish, 1796, and one from him, 1787, business and legal documents, largely concerning the estate of James McGill, 1810-1834, and a diary, 1806-1810, mostly a record of where he dined.

McDonald's correspondence, 1791-1860, mostly concerns business and property matters, but also includes personal correspondence. There are statements of account with McTavish, Frobisher & Co., 1799; with McTavish, Fraser & Co., 1803-1804; with McTavish, McGillivray & Co., 1808-1809. There are two volumes of autobiographical notes assembled in 1859 and covering the period 1791-1816.

There is a second copy of the autobiography, probably transcribed in the late 19th century. Written on the front fly leaf is the name: A.E. MacDonald. It has 63 leaves, and there are minor textual variants.

Typed transcriptions of Charles McKenzie’s narratives about the Indigenous people of MIssouri, draft and revised draft before publication; Alexander Henry’s account entitled: “Account of a visit to the Mandan and Hidatsa Indians in 1806”; and John Macdonell’s “The Red River”. Also includes drafts for work entitled, "Early fur trade on the Northern Plains : Canadian traders among the Mandan and Hidatsa Indians, 1738-1818 : the narratives of John Macdonell, David Thompson, Franc̦ois-Antoine Larocque, and Charles McKenzie" / edited and with an introduction by W. Raymond Wood and Thomas D. Thiessen. Norman : University of Oklahoma Press, 1985.

The collection consists of documents amassed by Roderick Mackenzie. Among the Masson manuscripts there are other series of letters; as well as journals kept by North-Westers and various business documents. Some of this material exists as originals; others are contemporary copies - the George Keith letters for example are contemporary copies on paper watermarked 1827. The collection also includes some duplicate texts - contemporary copies or later nineteenth-century copies that in some cases represent edited versions of the texts. Samuel Wilcocke's account of the death of Benjamin Frobisher exists in a draft original (or contemporary copy) and in a late nineteenth-century clean copy. Of course Benjamin Frobisher did not die in the dramatic circumstances as recorded by Wilcocke, but peacefully in Quebec City in 1821.

There are three letters from Lord Selkirk, one from Lord Dalhousie, and eight from Lady Selkirk. The early letters concern the Red River Settlement and the North West Company. The letter from Lord Dalhousie, 1824, concerns legal matters, and the two late letters, 1828 and 1833, from Lady Selkirk are personal in nature.

The thirteen documents are depositions taken by Lord Selkirk concerning the conflict with the North West Company at the Red River Settlement in Manitoba and at Fort William. On 11 June 1815, representatives of the North West Company attacked and fired upon the colonists, and demanded the surrender of Governor MacDonell, who, to avoid the loss of blood, gave himself up voluntarily. He was taken to Montreal as a prisoner, and charges were laid against him by his enemies, but his case was not tried. These depositions concern this case.

The Coppenrath Collection of Voyageurs Contracts for the North West Company partners contains 52 contracts for the period from approximately 1800 to 1821. These document the terms of engagement for men going into the North West . Voyageur contracts are of particular interest for study of the fur trade, Canada's first major industry, because they document the conditions of employment for many of the journeymen ("engagés") involved in the trade, both those who worked on the Ottawa River and those who "wintered" in the North West. The contracts are dated from 1800 to 1821 with printed forms from before 1800 being used in some cases. A significant number of outfitters are included namely the firm of McTavish, McGillivrays & Co. with various partners including John Ogilvy and Thomas Thain, Pierre de Rocheblave and earlier partnership – McTavish, Frobisher & Co. As well, there are contracts with lesser known outfitters. These contracts provide not only the names of the "engagés" but usually their place of residence and the conditions and terms of their employment.

There is business correspondence, 1792-1800, with letters from among others Alexander Mackenzie, Joseph Frobisher, Alexander Henry, Simon Fraser and Roderick Mackenzie. There are also minutes and resolutions of the Executors of McTavish in a bound volume; and a contemporary copy of the minutes of the executors of his will, 1805.

Contains copies of fur trade documents bearing on the Mandan-Hidatsa trade with North West Company posts in central Canada, 1793-1805. Includes the journals of John Macdonell (McGill), David Thompson (Archives of Ontario), François-Antoine Larocque (LAC & Université de Montréal, Baby Collection. Draft before publication of: Early fur trade on the Northern Plains: Canadian traders among the Mandan and Hidatsa Indians, 1738-1818 : the narratives of John Macdonell, David Thompson, Franc̦ois-Antoine Larocque, and Charles McKenzie / edited and with an introduction by W. Raymond Wood and Thomas D. Thiessen. Norman: University of Oklahoma Press, c1985.