1. On December 15, 1896, Utah was admitted as the 45th state of the United States. This followed decades of controversy surrounding the practice of polygamy in Utah, and the eventual decision by many Mormon leaders to abandon the practice in order to gain acceptance from the federal government.

2. On December 15, 1971, the first winter ascent of Mount Timpanogos was completed by Jeff Lowe and Mike Weis. This difficult climb is considered a major achievement in the history of mountaineering and has inspired many subsequent climbers to attempt the same route.

3. In 1884, the first Mormon temple built in Utah outside of Salt Lake City was dedicated in Logan on December 15. Today, the Logan Utah Temple remains an important center for Mormon worship in the state and is a popular site for those interested in learning more about the religion.

4. On December 15, 1967, construction began on the Kennecott Copper Mine's Magna Mill. This massive mine has been a major contributor to Utah's economy for many decades and remains one of the largest producers of copper in the world.

5. December 15, 1922, was a significant day in the history of aviation as pioneering aviator Frank Hawks made a record-breaking flight from Los Angeles to New York in under 22 hours. Hawks' achievement demonstrated the growing importance of aviation in American life and helped fuel interest and investment in the industry.