Papers of Edward R. Geary include correspondence and other materials pertaining to his life and activities, as well as financial records and correspondence relating to the Office of Indian Affairs, primarily from the period in which he was the Superintendent of Indian Affairs for Oregon and Washington. Personal correspondence includes copies of letters to Geary from his brother, John W. Geary, containing details of John Geary's experiences in Panama, Mexico, Harrisburg, and as the first mayor of San Francisco; and a typescript copy of an 1851 letter from Edward Geary to John McClellan, describing his voyage to the Pacific coast via the Isthmus of Panama. Other materials include speeches and sermons; papers relating to the estate of John Webster Perit Huntington and to the Oregon Central Railroad; and Geary's will.

Materials in the collection that relate to the Office of Indian Affairs include Geary's certificates of nomination and appointment as superintendent; correspondence; and extensive documentation of the Oregon agency's expenditures from 1859 through 1861. Vouchers contain itemizations of purchases, including gifts and provisions given to Native peoples in fulfillment of treaty obligations. Lists include names of individuals and their tribes. A letter dated July 9, 1861, from Indian agent A. J. Cain (filed in "Cattle Contracts of July 2, 1860") describes relations between Native people and emigrants. The records are meticulously written and probably reflect the work of Geary's clerk, Quincy A. Brooks.