Final answer:
Brigham Young led thousands of Mormons to settle in Utah after Joseph Smith's death, guiding them on the Mormon Trail to the Salt Lake Valley.
Step-by-step explanation:
The man who led thousands of Mormons to settle in Utah after the death of Joseph Smith was Brigham Young. Following the tragic killing of Joseph Smith by an anti-Mormon mob, Brigham Young assumed leadership of the Church of Latter-Day Saints. He was instrumental in orchestrating the movement of the Mormons westward, leading them through the 1,300-mile journey known as the Mormon Trail to the Salt Lake Valley in what was at the time part of Mexico. This massive migration occurred mainly between 1846 and 1860, with the first group comprising 12,000 members. Young's leadership and pioneering spirit established a new hub for the Mormon faith in a sparsely-populated area, fulfilling the church's vision of creating a 'pure kingdom of Christ' in America.