On January 4, 1896, following the Mormon abandonment of polygamy, Utah was admitted as the 45th state. From the article:
"Utah enters the Union
Six years after Wilford Woodruff, president of the Mormon church, issued his Manifesto reforming political, religious, and economic life in Utah, the territory is admitted into the Union as the 45th state.
In 1823, Vermont-born Joseph Smith claimed that an angel named Moroni visited him and told him about an ancient Hebrew text that had lost been lost for 1,500 years. The holy text, supposedly engraved on gold plates by a Native-American historian in the fourth century, related the story of Jewish peoples who had lived in America in ancient times. In 1827, Smith receives the gold plates from Moroni and, over the next 85 days, Smith dictated an English translation of this text to his wife and other scribes. In 1830, The Book of Mormon was published. In the same year, Smith founded the Church of Christ, later known as the Church of Jesus Christ of Latter-day Saints, in Fayette, New York.
The religion rapidly gained converts and Smith set up Mormon communities in Ohio, Missouri, and Illinois. However, the Christian sect was also heavily criticized for its unorthodox practices and on June 27, 1844, Smith and his brother were murdered in a jail cell by an anti-Mormon mob in Carthage, Illinois. Two years later, Smith’s successor, Brigham Young, led an exodus of persecuted Mormons from Nauvoo, Illinois, along the western wagon trails in search of religious and political freedom.
In July 1847, the 148 initial Mormon pioneers reached Utah’s Valley of the Great Salt Lake. Upon viewing the valley, Young declared: “This is the place,” and the pioneers began preparations for the tens of thousands of Mormon migrants who would follow.
In 1850, President Millard Fillmore named Young the first governor of the territory of Utah, and the territory enjoyed relative autonomy for several years. Relations became strained, however, when reports reached Washington that Mormon leaders were disregarding federal law and had publicly sanctioned the practice of polygamy. In 1857, President James Buchanan removed Young, a polygamist with over 20 wives, from his position as governor, and sent U.S. army troops to Utah to establish federal authority. Tensions between the territory of Utah and the federal government continued until Wilford Woodruff, the president of the Mormon church, issued his Manifesto in 1890, renouncing the traditional practice of polygamy, and reducing the domination of the church over Utah communities. Six years later, the territory of Utah was granted statehood."