Dr. Hinsdale was quick to perceive the unique historical importance of the letters which passed between her father and his early mentor and lifelong friend. The correspondence, which began when Hinsdale was nineteen and continued with increasing regularity during Garfield's years as a member of the House of Representatives and until his death in 1881, was coincident with a period of Republican supremacy and Congressional domination. The importance of the contribution of the letters to an understanding of the social history of the Western Reserve could not fail to be appreciated by the daughter of the author of The Old Northwest, herself a distinguished teacher and historian.