Personal papers contain personal correspondence, correspondence with Theodore Roosevelt, tributes and obituaries, writings, memoranda and inventories, receipts, and printed material. Personal correspondence between Henry Davis Minot and acquaintances from 1866-1890 discusses daily activities and personal matters. Most of the correspondence is written to Henry D. Minot, primarily from his parents William and Katharine Sedgwick Minot, his brothers Laurence and William (1849-1900), sister Alice, and Herbert and Edith Parker. Some of the Parker correspondence includes typescript copies and originals.

Correspondence between Minot and Theodore Roosevelt from 1877-1886 discusses Harvard University, ornithology, Roosevelt's engagement, and the death of Alice Roosevelt. Most letters are copies provided by the Trustees of the Roosevelt Memorial Association.

Obituaries and tributes to Henry D. Minot include correspondence written to the Minot family upon his death, calling cards, and accounts of the train collision.

Minot's writings from 1867-1887 include pieces from early childhood, papers from Harvard, essays, a draft of the history of North America, religious thoughts, poetry, criticism, and two drafts of aborted novels.

Bound personal papers of Henry D. Minot include letterbooks, diaries, journals, personal account books, school notebooks, and a scrapbook of obituaries of him. Three letterbooks from 1884-1889 contain letters written by Henry D. Minot to his father, William Minot, Jr. Henry D. Minot journals from 1876-1882 describe daily activities, the landscape, birds seen and/or heard, trips to England and Scotland in 1879, Colorado in 1880, and Dakota and Minnesota in 1882, via railroad.

Ornithology papers contain correspondence exchanged between Henry D. Minot and other ornithologists largely regarding Minot's book, The Land-Birds and Game-Birds of New England; drafts of ornithological writings by Henry D. Minot, including nomenclature of birds, draft of book dedications, and notes on Colorado birds; and a record of bird watching kept at West Roxbury from 1873-1875. Newspaper clippings and printed material contain articles from the Worcester newspaper about talks delivered by Minot at the Worcester National History Society, reviews of his books, and debates about English sparrows in the United States.

Railroad papers contain letters and telegrams between Henry D. Minot and railroad officers, including James Jerome Hill, regarding railroad development, maps, investments, land surveys, and internal business affairs, as well as letters between Minot and railroad investors, primarily from the New England region. Railroad reports contain information regarding financial matters including expenses, earnings, and stocks. Most reports have several drafts and a final version. Bound volumes include a railroad journal containing railroad time schedules, estimated cost of building materials, and an expense book for a trip to Mexico in 1884, which also notes descriptions of the landscape.

Maps from 1825-1889 contain printed and manuscript maps and survey plans collected by Henry D. Minot and used for his work in the railroad industry, including real estate and property surveys of mid-western and western states, some with proposed railroad lines drawn by Minot. Also included are maps of specific towns prior to incorporation and surveys of properties and estates in Massachusetts, particularly in the Boston area.