Svenung supposedly immigrated on the ship "Alert" in 1850 but his name is not found on the passenger list. Another source suggests he may have immigrated in 1851.
1860 CENSUS Winchester, Winnebago Co., Wisconsin, page 417: Swen Thompson, age 34, born in Norway Terena Thompson, age 24, born in Norway Matilda Thompson, age 5, born in WI Charles Thompson, age 3, born in WI Thomas Thompson, age 1, born in WI