Rasmus arrived in Philadelphia on 31 May 1857 via the ship Westmoreland. Both the ship passenger list and the British Mission Record (Mormon Migration) show his surname as Clausen. He came to Utah by 1865, but the first documentation to place him in Utah is the birth of a child in January 1866, which was prior to the arrival of that season's emigration. Further research is needed to narrow the year of his travel. In some sources his surname is spelled "Clawson."