The 23 diaries of Thomas Lynch Montgomery measure 2.6 linear feet and date from 1903 to 1929. With few exceptions, Thomas Lynch Montgomery was a regular diarist, and while the content of his writing focused on his professional life, references to his family, friendships, and social life are mentioned throughout. Montgomery focused on events from his tenure as State Librarian, and many subsequent entries follow a format of noting the time he spent at work, his list of daily correspondents, his social engagements, and other activities of note.  

Many of the diaries include material from events in Montgomery’s personal life, which he inserted or pasted into the diaries. These inserts include personal and professional correspondence, theater programs, invitations, newspaper clippings, postcards, photographs, and other miscellaneous ephemera.  Invitations were to events held by the various clubs and societies Montgomery was a member of and that he attended. He also collected postcards featuring landscapes and saved newspaper articles, most of which feature himself as the subject.

In letters from his close friends, many address him as Tom. Montgomery’s two main correspondents were Martin Brumbaugh, the twenty-sixth Governor of Pennsylvania, and Edward Nolan, a librarian at the Academy of Natural Sciences in Philadelphia. Topics are primarily professional and regard inquiries or the library, though he also included frequent mentions of his social engagements and club speeches in particular. More personal letters are concentrated around the death of Brinca in 1921. 

In his entries, Brinca Gilpin is referred to as ‘B,’ and he also often references his cat when writing about his first wife. Susan Keim Savage is referred to as ‘S’ and occasionally Sue. A Catholic and Republican, in the later diaries, Montgomery notes the frequency of attending church and theater performances with Susan, and he also mentions eating meals with Brinca’s sister, Elizabeth Gilpin, with regularity. 

Montgomery used primarily Excelsior journals in both weekly and daily formats. In both forms, the volumes have predated calendars and space in the front/back for reference charts, notes, and record keeping, which he kept blank.