Magnús Þorsteinsson was born on January 25, 1842 in S. Múlasýsla. He died in Lincoln County, Minnesota on June 18, 1894.
Spouse: 1) Guðný Eiríksdóttir b. 1847, d. September 25, 1875 in the Mt. Askja eruption 2) October 26, 1876 Vilhelmína Guðmundsdóttir b. July 22, 1853, in S. Múlasýsla, d. February 1, 1920.
Children: With Guðný: 1. Eiríkur (Eric) b. March 14, 1870. Three other children died in the 1875 Mt. Askja eruption. With Vilhelmína: 1. Gróa b. March 6, 1877, d. October 31, 1958 in Lincoln County 2. Guðmundur b. c1878 3. Kristján (Christian) b. May 24, 1881, d. April 18, 1887 4. Jón (John) b. March 5, 1883, d. December 1, 1957 5. Lilja (Lillian) b. April 18, 1885 6. Alfreð b. August 18, 1887 7. Kristín (Christine) Boel b. July 19, 1888 8. Þorbjörg (Thora) b. July 14, 1890, d. April 7, 1953.
They came west to Minnesota in 1878 and first settled in Lyon County. They later moved to Lincoln County.