1. On September 21, 1864, the Battle of Big Dry Creek took place in eastern Montana. It was one of several conflicts fought between the U.S. Army and Native American tribes during the Indian Wars.

2. In 1913, on September 21, the Great Falls Symphony Orchestra was founded in Great Falls, Montana. It has since become one of the state's premier cultural institutions, hosting concerts and events throughout the year.

3. On September 21, 1938, a massive forest fire known as the Blackwater Fire swept through western Montana, burning over 100,000 acres. It was one of the most destructive fires in the state's history, and it took weeks to fully extinguish.

4. In 1967, on September 21, the Anaconda Smelter Stack in Anaconda, Montana, was demolished after over 75 years of operation. At the time, it was the tallest freestanding masonry structure in the world, standing at over 500 feet tall.

5. On September 21, 1997, the Going-to-the-Sun Road in Glacier National Park was designated as a National Historic Civil Engineering Landmark. The scenic roadway is one of Montana's most popular tourist attractions, offering stunning views of the park's mountains, glaciers, and wildlife.