The Albert Leffingwell Collection was originally well preserved and well organized by Leffingwell himself. The correspondence and other documents reveal the state of animal rights and mental healthcare in the U.S. in the Victorian era. The scope of the collection is wide, ranging from some early settlement claims in Aurora, NY to the grounds eye view of the Russian Revolution of 1905 and the persecution of Jews in Warsaw.

Contains items from the Borthwick, Smith, and Strong Families including correspondence, diaries, family histories, financial papers, land records, a school notebook, and a manuscript cookbook. Additional material includes two woman's diaries, land records, a history of the Bushnell Family, and Hattie E. Kurtz's school notebook. Of unusual interest is a black & white photograph of Abraham Lincoln taken by Matthew Brady in Washington, DC in 1864.

Personal and business papers of members of these related families, especially Charles Bush Collins, Lyman R. Lyon, Clinton L. Merriam, Charles C. Merriam and his wife Florence Lyon Merriam. Includes letters, diaries, military commissions, wills, inventories, cash accounts, deeds, and field books relating to their large land holdings in Lewis County, N.Y., their lumber business, and their involvement in politics. Also contains a large number of household bills of the Lyon family.

George William Featherstonhaugh (1780-1866) was a British-American geologist and geographer. Featherstonhaugh served as the first geologist to the U.S. government and was one of the proposers of the Albany and Schenectady Railroad. This collection includes correspondence and other family-related documents.

Scott Dumont Goodwin (1845-1935) was the legal representative and attorney for a number of influential Albanians and others whose affairs and estates are represented in this collection. Also included is the correspondence and diaries of Lieutenant George Wait Goodwin U.S. Air Force, who was killed in France in 1918, and Edward S. Goodwin, Albany physician, Helen Goodwin Yale, and Louise Goodwin, who were all children of Scott Dumont Goodwin. This collection includes correspondence, diaries, accounts, and legal papers.

Arthur Julius Hacker (1916–1999) and Marilynn Agnes Pyne (1918-2002) married in 1947. They had two children, both born in Albany: Craig Arthur Hacker (1951- ) and Arlynn Jean Hacker (1948- ).

Harry Douglas Yates (1903-1996) was a banker, politician, and developed the Dutch Village apartment complex in Menands, New York. This collection contains diaries, correspondence, deeds, scrapbooks, and other related papers.

Hendrickson was born in Albany, in 1866, and spent the majority of his years living and working as a professional photographer in and around the downstate city of Yonkers. This collection includes material relating to the photographer’s artistic and commercial work rather than his personal life.

Hybertie Lansing Pruyn Hamlin (1873-1964) was born in Albany, New York, to John Van Schaick Lansing Pruyn (1811-1877) and Anna Fenn Parker Pruyn (1840-1909). Her father was a U.S. Congressman, representing New York’s 14th District. One of her sisters was Harriet Langdon Pruyn Rice (1868-1939). Hybertie married Charles Sumner Hamlin (1861-1938) in 1898. Charles was a lawyer, delegate to three international peace conferences, and later, the first Governor appointed to the Federal Reserve Board in 1914.

John Mason Clarke was the Director of the New York State Museum from 1904 until his death in 1925. This collection includes correspondence, clippings, and diaries.