Papers consist of incoming correspondence (1912-1950), concerning politics, sheep raising, and fraternal activities; scattered outgoing correspondence (1917-1945); court papers (1918-1930); financial records (1910-1950) consisting primarily of county taxes, receipts, livestock shipments and inventories, wool production figures, and promissory notes; legal documents (1913-1943) primarily concerning land leases; maps and plats of Larson land holdings; printed material; and speeches concerning political campaigns and history. In addition, there is a subject file (1909-1946) focusing on politics and ranching matters. This file includes folders on several companies, in which Larson held an interest, including the Birch Creek Water Company, the Brady Irrigation Company, the Brady Townsite Company, and the Teton Co-operative Reservoir Company. It also includes files on Larson's leasing of grazing land on the Blackfeet Indian Reservation, including lists of Blackfeet tribal allotment holders. There is also a file on the Sun River elk herd, including reports on the condition of the herd. Miscellaneous material includes certificates and membership cards, fraternal order materials, humor and poetry, a booklet of the Sun River Sanitarium Association, and other items. Clippings include reviews and announcements for A.B. Guthrie Jr.'s The Big Sky, and a scrapbook (1936) of clippings concerning Larson's race for the U.S. Senate.