Clausen served congregations across Wisconsin, Iowa, and Minnesota, founding several churches and emerging as a central figure in organizing early Norwegian Lutheran synods, including key work with what later became the Evangelical Lutheran Church in America. He was also instrumental in establishing educational and cultural institutions that supported immigrant identity and religious life, among them early efforts that contributed to the founding of Luther College.

Beyond his pastoral work, Clausen was a publisher and editor, helping launch the influential Norwegian-language newspaper Maanedstidende, which provided news, religious writings, and community connection to scattered settlers. During the U.S. Civil War, he served as chaplain to the Scandinavian Regiment, the 15th Wisconsin Volunteer Regiment, ministering to soldiers in battle and hospital camps.

Scope and Content: 
Papers of and materials about the Danish-born clergyman, the second pastor ordained to serve Norwegian-Americans. Includes his emigration diary, letters, ministerial record books, photographs, clippings, and articles.