Why did Brigham Young lead Latter-day Saints from Nauvoo to the Great Salt Lake Valley?

Brigham Young led the Latter-day Saints from Nauvoo, Illinois, to the Great Salt Lake Valley primarily because increasing mob violence made their continued presence in Illinois untenable following the murder of Joseph Smith in 1844.1

The migration, which took place between 1846 and 1847, was driven by the desire to establish a commonwealth where the Saints could practice their religion without persecution. By settling in the Great Basin, Young and his followers sought to build a "kingdom of God" in a location that offered the comparative isolation necessary to stabilize their society and maintain their unique social and political institutions.123

Upon arriving in the valley in 1847, Young selected the site of Salt Lake City as a central gathering place, envisioning a new state called Deseret that would serve as a secure base for Mormon colonization.213