1. In 1883, Helena was officially incorporated as a city. Helena is the capital of Montana and is home to the Montana State Capitol and the Montana Historical Society Museum.

2. In 1897, Montana State University was founded in Bozeman, Montana. The university is now one of the largest institutions of higher education in the state.

3. In 1941, the United States declared war on Japan after the attack on Pearl Harbor. Montana played a significant role in the war effort, with its soldiers serving in many branches of the military and its industries contributing to the war effort.

4. In 1962, the Anaconda Copper Company announced the closure of its copper smelter in Anaconda, Montana. The smelter had been a major employer in the area, and its closure had a significant impact on the local economy.

5. In 2014, Montana became the first state to allow same-sex marriage through a court decision. The ruling followed the U.S. Supreme Court's decision earlier that year overturning the Defense of Marriage Act.