In 1855, Brigham Young—President of the Church of Jesus Christ of Latter-day Saints—instructed Church Apostle Erastus Snow to begin preaching in the country of Denmark. The Christensen family joined the Church the same year, and soon later immigrated to the United States to live with the Saints in Utah. They joined the Captain Christian Christiansen Handcart Company to head west to Utah. 

As the family neared the Salt Lake Valley, they got word about Johnston's Army and them coming to Utah, and they would have to hurry and move south as soon as they got to the valley. The family entered the valley on Sep 13, 1857. 

"Peter said that when the general came to Brigham Young's home, he paused in front of it, got off his horse, took off his hat, and drove his sword into the ground, and gave a salute 'to the home of a man who was such a great colonizer.'" 

After the conflict now known as the Utah War, the Salt Lake Valley went back to its usual days. As the other Christensen family members moved elsewhere in the state, Peter remained in Salt Lake City working with Brigham Young.

Sometime between 1860 - 1865, Peter moved to Richmond and was housed with the Traveller family.