Erastus Snow was born at St. Johnsbury, Caledonia County, Vermont, on 9 November 1818 to Levi and Lucinda Snow. He joined the LDS Church in Vermont at the of age fourteen. As an early member of the church, Snow suffered the persecution in Ohio, Missouri, and Illinois, and he was instrumental in the organization of "Camps of Israel" for the trek west.

Snow was with the vanguard company of Mormon pioneers led by Brigham Young. On 21 July 1847 Snow and Orson Pratt, alternately riding a single horse and walking, followed the Donner Party trail over Little Mountain and down Emigration Canyon, and they were the first of the Mormon pioneers to enter Salt Lake Valley.

Snow participated in the organization of the State of Desert in 1849, and, representing southern Utah, was a member of the Utah territorial legislature.

He was a colonizer in Utah, New Mexico, Colorado, and Arizona; and he established southern settlements on the Virgin and Santa Clara rivers for the purpose of raising cotton. With George A. Smith, Snow organized the Deseret Iron Company in Iron County, and founded St. George in 1861. Snow was an outstanding leader and directed the settlements in southern Utah for many years. Sanpete Academy was renamed Snow College in 1902 in honor of Erastus Snow and LDS Church president Lorenzo Snow.