From the DPL website: Description:

The Burton Historical Collection of the Detroit Public Library began life as the private library of Clarence Monroe Burton. In addition to being a prominent attorney, Mr. Burton was a Detroit historiographer and the founder of the C. M. Burton Abstract Co. Mr. Burton’s original intention was to assemble a collection on the history of Detroit. Realizing that Detroit’s history was inextricably connected to that of Michigan and the Old Northwest and those histories to that of Canada and New France, he assembled a collection that was one of the most important private historical collections in the county.
Over the course of 40 years, Mr. Burton systematically collected original documents and personal papers of prominent citizens of Detroit and Michigan. By 1914 the library contained 30,000 volumes, 40,000 pamphlets and 500,000 unpublished papers. Mr. Burton donated his collection, including the building it was housed in, to the Detroit Public Library in 1915. The collection was moved to the new main library in 1921.