Mahlon Day was a printer and publisher of children's books, including many moral tales. He was an active member of the Society of Friends, and served as clerk of New York Yearly Meeting. His interests led him to serve as a trustee of African Free Schools and as a manager of the New York Institution for the Blind, among other activities.
Day, born in Morristown, New Jersey, on August 27, 1790, was the son of Samuel and Nancy Day and brother of Stephen Munson, Samuel Jr., Susan, Phoebe, Abraham, Jared, Jehiel, Ira, and Nancy Jr. In 1815, he married Mary Kerr. Their children were Mary Jr., Sarah, Anna, Susan, Edward, and Jane. This latter Jane married William Thurston; thus the small collection of Thurston letters, documents, and photographs among these papers.
In 1839-1840, Day traveled to the West Indies with Joseph John Gurney, a Quaker minister and anti-slavery advocate.
In 1854, when Mahlon Day, his wife Mary, and daughter Susan were returning from England, their ship, the Arctic, was rammed by another boat. The Arctic sank, taking the three Days with it. There are letters of sympathy in this collection, primarily to the Day children.