Final answer:
Utah saw transformation in the early 1800s as Mormon pioneers led by Brigham Young settled in the region, establishing a unique social and political order after becoming part of the United States post-Mexican-American War.
Step-by-step explanation:
In the early 1800s, Utah began to undergo significant changes with the influx of Mormon pioneers, led by Brigham Young. In the aftermath of the Mexican-American War and the signing of the Treaty of Guadalupe Hidalgo, the modern-day American Southwest, including Utah, became part of the United States. Utah was officially recognized as a territory by Congress in 1860, and Brigham Young was appointed as territorial governor by President Millard Fillmore. The Mormon migration brought a unique social and political order to Utah as they established settlements near the Great Salt Lake, following the religious persecution they faced in the East. This period also saw the Mormon Trail being used extensively by the Mormons moving towards Utah from Nauvoo, a journey of significant cultural and religious importance for the Latter-Day Saints.