Petersen is a name of patronymic origin meaning literally son of Peder (or Peter). My Petersen ancestors are from Denmark and changed the spelling from Pedersen to Petersen upon arrival in the United States. The Patronymic system of naming was still in use in Denmark until about 1850. For more information on patronymic surnames, especially in Denmark, see Diana's Genealogy Pages: Patronymics.

Andrew Petersen b. 18 Dec 1832 in Voerbjerg, Skanderborg Ring, Denmark. He immigrated to Utah in 1866 and settled in Summit County. His line was traced back several generations by a professional genealogist and can be found in Ancestral File. This line was one of the first I took interest in because my father gave me a copy of the pedigree charts and group sheets compiled by this researcher. See [Ancestor 3] .