Louis is the son of Hans Rasmus Larsen and Kathrine Jensdatter Larsen. They crossed the Atlantic from Liverpool to New Orleans on the ship Benjamin Adams in 1854. The ship manifest shows his given name as "Lars."
Hans paid tithing at Ceder City, Utah in 1855 and the family was still there at the time of the 1856 Utah Territorial census: Hans, "Catherine," and "Lois." By 1857 they were living at Fort Ephraim in Sanpete County where Hans is listed on the Territorial Militia roll. In the latter year Hans was ordained a Seventy and became a member of the 47th Quorum. Louis married in 1866. In some sources his name is spelled as "Lewis." Further research is needed to identify the name of the pioneer company with which the family traveled.