Johannes Olsen was a Danish immigrant who settled in Dagmar, Montana, and later settled in Tyler, Lyon County (1948). The collection contains papers dealing with his farm in Montana, and operation of a coal mine and co-operative store in Dagmar, Montana from about 1906 to 1949. Also contained in the collection is correspondence on settlement of three relatives' estates in Denmark and California. The papers cover the period 1906 to 1950, with some papers dated 1885.