The main reason that it took so many years for Utah to become a state (in 1896) was simply the fact that Utah was different. It was essentially the holy land of the Church of Latter Day Saints (commonly called Mormons).
What was Utah before it became a state? The Church of Jesus Christ of Latter-day Saints wanted to join the United States as the state of Deseret, but instead the land became the Utah Territory. It wasn’t until January 4, 1896 that Utah was admitted as the 45th state.
How did Utah become a part of the United States? In 1848, the United States gained control of Utah from Mexico as a result of the Mexican-American War. Over the next several years, disagreements between the U.S. government and LDS Church leaders kept Utah from becoming a state.