Soon after William was born, the Thompson family joined the Church of Jesus Christ of Latter-day Saints. When William was almost 10, his mother died. William's father did not remarry until 1850. The following year, the Thompson family began their journey to Utah. They moved to Council Bluffs, Iowa and joined the Harry Walton/Garden Grove Company. They set out on May 17, 1851 and arrived in the Salt Lake Valley on Sep 24. William lived in Boutiful, Utah, until 1860 when he moved to Richmond.