Peter M. Crist was born on April 20, 1807, in New York to Henry H. Crist. His father was a farmer who owned $2,000 of real estate by 1850. He married Lillian Hunter on January 8, 1829, and they had at least five children: Robert Henry, born on December 19, 1829; Mary Elizabeth, born on March 2, 1834; Parna Jane, born on March 2, 1834; Deborah Ann, born on October 4, 1836; and Catherine Helen, born in May 1840. His wife died in 1843, and he married Nancy Jane Frazier on October 13, 1843. Their son Lee was born around 1853.
The family lived in Bethel, New York, until around 1845, when they moved to Plainfield, Illinois. By 1850, he was working as a carpenter, and he owned $1,600 of real estate. A decade later, he owned $3,500 of real estate and $300 of personal property. He supported the Democratic Party until the mid-1840s, when he switched his allegiance to the Whig Party. When the Whig Party collapsed in the 1850s, he joined the Republican Party. He moved to Durant, Iowa, in the 1860s, and by 1870, he owned $11,600 of real estate and $1,315 of personal property. He died in Durant on October 17, 1875.