Among all the various figures in 19th century America who left controversial legacies, it is hard to find one as influential as Joseph Smith (1805-1844), the founder of The Church of Jesus Christ of Latter-Day Saints, Mormonism, and the Latter-Day Saint movement. Revered as a prophet on the level of Moses by some, reviled as a perpetrator of large-scale fraud by others, what everyone can agree on is that Joseph Smith founded a religious movement that played a crucial role in the settlement of the West, especially in Utah.

Smith's death was one of the catalysts for the Mormons' great migration to Utah, and today that state and the Mormons are virtually synonymous. To this day, Mormons still form a majority of the population, and members of the Church have prominent political and economic roles. Among the most effective methods by which the Latter-Day Saints attained regional dominance was the flooding of specific areas with a like-minded population of fellow settlers and offspring, subsequently controlling the voting and government institutions through a weighty majority. Such an approach caused alarm in each region to which Mormon settlers emigrated; the church collective had already been evicted from New York and other areas for exercising the tactic. The practice of polygamy within the church may have been socially repugnant to Judaic and Christian denominations, but the schism between Mormonism and other American faiths lay deeper. This theological separatism caused the Mormon community to live apart, except in the pursuit of converts. The church became increasingly perceived as "un-American," and over time hostile to and dismissive of those living outside the faith. In time, the Mormon belief that its members were the only heirs to the kingdom of God justified the commission of crimes, including murder. The non-Mormon population responded in kind.