The Lothrop Family Papers consist of letters, commissions, reminiscences and a portrait. There are 17 letters from Elias Lothrop to his wife, mother, and brother. Three of these letters are dated 1843-1847 from Chicago and Georgetown, Maine, and 14 others are from California, dated 1849-1853. He writes of mining, life in California, his illnesses, local news, and his need to make more money before he can afford to go home. A letter dated May 1849, carries a detailed description of life on board ship en route to California. His last letter, headed "Secret Digings [sic] Jan 6th 1852," carries a long account of his thoughts on California, with the summation that "everything seems to run to extremes here," in terms of fortune, health, weather, etc.
There are five other letters, two to Jane Lothrop dated 1852-1853,from T. P. Robb and Charles O. Turner regarding her husband's death. Another letter, written by R. J. Morse in New Orleans dated 1853 mentions the rental and purchase of "colored servants." A letter written by Warren Lothrop mentions that he is with Colonel Callender in St. Louis. Another letter written by Warren is here only in part, and describes the battle of Vera Cruz. The letters are accompanied by a recipe for a cholera cure, an engraved portrait of Levitt Lothrop, two of Warren Lothrop's commissions, and reminiscences of a part of the Mexican War by John Smith of the U.S. Army, whose relationship to the Lothrop family is unknown.