1. On September 27, 1904, the town of Havre in northern Montana was incorporated. Havre is known as the location of Montana State University-Northern and the Havre Beneath the Streets underground city tour.

2. The Great Fire of 1910, also known as the Big Blowup, was a catastrophic wildfire that destroyed several towns and killed over 80 people in Idaho, Montana, and Washington. On September 27, 1910, the fire raged across Montana, destroying the town of Taft and killing several firefighters.

3. In 1964, the Montana Constitution was ratified on September 27, marking a significant milestone in the state's history. The new constitution established a three-branch system of government and protected individual rights and freedoms.

4. On September 27, 1975, Governor Thomas L. Judge signed the Montana Human Rights Act into law, which prohibited discrimination based on race, religion, gender, or disability in employment, housing, and public accommodations.

5. Glendive, Montana, located in Eastern Montana along the Yellowstone River, became the first town in Montana to have electric street lights on September 27, 1900. This was a major development for the town and contributed to its growth as a regional hub for agriculture and transportation.