Series 5 consists of thirty-one travel journals and diaries, spanning 1851 to 1912. Early in life, Mitchell kept a journal only when he travelled; the earliest journal in the collection documents his 1851 trip through Europe with his sister Elizabeth. Also present are journals of his frequent camping and fishing trips, made between 1869 and 1874, to the Great Lakes region of Canada and the United States. Included in Series 5 is a journal from Mitchell's 1879 trip to Yellowstone Park, Wyoming, and several journals recounting trips to Europe made between 1880 and 1891. Many of the journals contain poem manuscripts, probably written during Mitchell's travels.
Mitchell did not make a serious attempt to keep a daily diary until the mid-1890s. Series 5 contains all of his diaries spanning 1894 to 1912, with the exception of the 1902 and 1913 diaries. (Mitchell's 1913 diary was part of an earlier gift presented to the Historical Collections of the Library of the College of Physicians of Philadelphia by Mitchell's granddaughters, Mrs. Mitchell Macdonough and Mrs. Vinton Freedley.) The diaries are sketchy; Mitchell frequently went for days or even weeks without making an entry, and the entries he did make consist of fairly brief observations about his activities. Because of Mitchell's shaky hand, many of the entries in the later journals are hard to decipher; the later journals also contain entries written in another hand, perhaps by Mitchell's personal secretary. The diaries reflect the pace of S. Weir Mitchell's daily life and provide a record of the people he met, the places he visited, and his general health and state of mind.