Culture Minister Robert Henderson says the records provide insight into the province's business, social and political life.
The documents have been cared for by family descendants in Canada and the United States.
The records that have been donated document the lives of brothers Andrew Archibald, Archibald John and Augustine Colin MacDonald and their families.
The family is well known for their business interests in Georgetown and Panmure Island, as well as the political contributions made by the three MacDonald brothers in the 1800s and early 1900s.
The brothers served variously as members of the provincial legislature, House of Commons and the Senate.
The records include journals from the MacDonald Brothers Store in Georgetown and correspondence from Andrew Archibald MacDonald during his time as a senator.