1. In 1870, the first post office was established in the town of Bozeman, Montana. It was named after founder John Bozeman and served as a vital communication center for the growing population of the town and surrounding areas.

2. On May 11, 1889, the Montana Constitutional Convention convened in Helena to draft the state's constitution. The convention lasted for 66 days and resulted in the adoption of Montana's first constitution on August 17th of the same year.

3. In 1934, the Montana State Capitol building was completed in Helena after 6 years of construction. The building serves as the headquarters for the state government and features unique architecture, including the use of native sandstone and bronze for embellishments.

4. On May 11, 1967, notorious outlaw Henry Plummer was hanged in Bannack, Montana. Plummer was a member of the infamous "Innocents" gang, which terrorized the area during the gold rush of the 1860s. He was eventually caught and sentenced to death for his crimes.

5. In 1980, the Mount St. Helens eruption in Washington state caused significant damage to areas surrounding the volcano, including parts of Montana. Ash from the eruption fell heavily on the town of Missoula, forcing schools and businesses to close as cleanup efforts began.