Mabel's personal diary (1903-1948), which she labeled "Her Own Trip Book," seems to have begun as a travel diary and expanded over the years to record her daily activities. The earliest diaries in this series contain notes of Mabel's trips to New York City, Pennsylvania, New Jersey, and Massachusetts. These diaries are minutely detailed and report on the details of the places she visited more than on her or her companions' own personal thoughts and experiences . For example, Mabel faithfully copied the inscriptions on each monument, church, or other building she visited. While the early diaries in this set describe trips taken to visit family and friends, the later diaries describe her frequent trips to New York City for the purpose of sightseeing, attending services at Trinity Church and St. Paul's Chapel, and visiting the Brooklyn Botanic Garden. Mabel was a devout Episcopalian, and these diaries contain detailed notes (often in outline form) on sermons she attended. The very last diaries contain clippings from The New York Times and other newspapers. Many of these clippings are on the subject of global politics.

The poetry diaries (1907-1944) contain Mabel's poetry, written almost exclusively on the themes of nature and religion.

The final set of diaries (1930-1944) record Mabel's religious and spiritual thoughts.