1. On December 29, 1883, the Northern Pacific Railroad completed the first railroad bridge across the Yellowstone River in Billings, Montana. The bridge was a major engineering feat, spanning 2,600 feet and rising 170 feet above the water.

2. On December 29, 1890, the United States Army massacred approximately 300 unarmed Sioux men, women, and children at Wounded Knee Creek in South Dakota. While the massacre did not occur in Montana, it had a significant impact on the state's Native American communities.

3. On December 29, 1943, the University of Montana defeated St. Mary's College in the Sugar Bowl, one of the most prestigious college football games of the era. The victory marked the first and only time that the University of Montana has won a major national championship.

4. On December 29, 1963, the Anaconda Copper Company closed the Washoe smelter in Anaconda, Montana, putting more than 1,000 people out of work. The closure had a significant impact on the local economy, which was heavily reliant on the copper industry.

5. On December 29, 1975, the Montana Constitutional Convention adopted a new state constitution, which was ratified by voters in November of the following year. The constitution, which is still in use today, created a more democratic and representative government and expanded the rights of Montana citizens.