The Edward A. Milligan Papers, 1925-1977, have been arranged alphabetically by subject in each box. Much of the contents in Box 1 is correspondence, either general in nature or on specific topics. Note that some of the general correspondence will relate to topics found in other folders. The majority of the correspondence is incoming and is arranged chronologically within each folder. Milligan corresponded with people in different circles, stemming from his occupation as an educator, his personal interests, and from his participation in various organizations.

Other components include notes, drafts, and writings of Milligan. There are also materials he collected pertaining to Native Americans. In addition, there are five original ledgers of outgoing correspondence, 1874-1880, of the Indian Agent at Standing Rock Agency.

About 300 photographs are also part of the collection. Many of these pertain to Native Americans, especially depicting the 1936 Sun Dance at Little Eagle, South Dakota. Lastly, two oversize folders contain an assortment of maps, as well as drawings, posters, and military items.

Publications by Milligan:

The Standing Rock Sioux 1874-1890 (1948; UND thesis)

Known Migrations of Historic Indian Tribes... (1949 and 1969)

Petroglyphs, Pictographs, and Prehistoric Art in the Upper Midwest and Red River of the North Valleys (1968)

Sun Dance of the Sioux (1969)

The Indian in the Northern Plains (1972)

High Noon on the Greasy Grass: The Story of the Little Bighorn by Indians Who were There (1972)

Wounded Knee 1973 and the Fort Laramie Treaty of 1868 (1973)

A Brief Bibliography of Books on the Indian... (1973)

Dakota Twilight: The Standing Rock Sioux, 1874-1890 (1976)